Me and my players used to wonder about why numbers get so big in Pathfinder. Any Pathfinder player knows that rolls of 35 and 45 aren't uncommon at high levels. It's tempting to fall into the assumption that any big number is the same as a small number once you've found the lowest common denominator. However, my gaming group is into its fourth year of a Pathfinder 2 campaign as I write this, and we've finally started noticing and appreciating the nuance of those big numbers.
I think some people fall into the trap of thinking Pathfinder 2 is over-complex, and that it heaps modifier on modifier just for the sake of being able to claim flexibility. Pathfinder can legitimately lay claim to precision controls over your character build. It has some simple and kind of obvious-once-you-think-about-it features, like a unique proficiency bonus for each skill, weapon, saving throw, and armour type. The counter-argument to that kind of design is that probably people don't care for that degree of precision, or at least not enough to make the perceived extra work worth the perceived effort.
Anyway, that's not why big numbers matter in Pathfinder. It is related, however, to why big numbers are scary to a lot of players.
Big numbers only get big after a lot of math, and not everyone enjoys crunching numbers or even to do work in advance to make the math simple. I think 5e found exactly the right amount of math for most people. It's not no math, because that would have upset existing dnd players, but it is math you can mostly do with your fingers. There's just enough math that some players still struggle with it under pressure, which makes it feel like dnd, but it's usually math you can solve ecentually, and then excuse with a throwaway comment about how you're bad at maths. That's a liberating feeling, and a real solution to a potentially uncomfortable social interaction.
Pathfinder does what it can. Proficiency rankings are scored in increments of 2 (2, 4, 6, 8), and attack pelanties are -5 and -10, and critical successes or failures are measured by 10 (10 over or 10 under the DC.) But ultimately you're still adding numbers that you probably haven't memorised the sums for, like 6 and 8, or 5 and 7, and basically anything but +1 and +2 like in 5e.
The interesting thing about the numbers in Pathfinder is that they're a lot more loaded with data than the numbers in a simple system like 5e. The beauty of 5e is that it's basically a what-you-roll-is-whatyou-get system. Yes, you get modifiers, but almost every 5e player writes off any roll under 10. We don't even bother doing the math, because the assumption (that's often correct) is that what you see on the d20 is ultimately what the game master is going to use. Adding modifiers is your Hail Mary, a desperate attempt to persuade the game master that you don't deserve the punishment your d20 roll has earned.
In Pathfinder 2, every roll is a reflection of your character's experience. If you've been picking locks for 10 levels, it's unlikely you're going to botch a roll to pick a lock because you've got a baseline +10 bonus. At level 15, you're rolling with a +15. By that time, if you do fail a roll, even by rolling a 2, then you know you're dealing with a highly specialised lock.
It's similar for monsters. In 5e, when you fail to hit a monster with a 19, you know it's no more threatening than approximately 10 modifier points, because between attribute modifiers and proficiency, that's as much as you're ever going to add to a hit roll. That's still scary, but but it's pretty definitive, and everybody knows that the unknown is more terrifying than anything. In Pathfinder, you can swing and miss a monster at level 2 or at level 15, and the sky's the limit. A monster could be CR 10 or CR 20 or CR Anything. You don't know, because the ceiling is set so high in Pathfinder 2. That gives the game master a lot of room to play with, and it can turn players into more thoughtful strategists. Breaking down doors and killing whatever's inside is less of a certainty in Pathfinder, so you investigate, study, and test whatever obstacle's in front of you before jumping in head first. (Or, let's face it, you don't. But at least you know you shoulde)
The eternal question, like so many questions in game design, is whether anyone cares. If nobody playing notices the upper ceiling on threat levels, and everyone either doesn't bother leveling up or stops playing at level 20 as intended, then the constraints of the physical numbers on a d20 (plus or minus 10 or so modifiers) do the job. Is the cost of a greater scale worth the price of extra math and system complexity? I think the obvious answer to that exact question is no. If nobody's using the benefit, then it's silly to pay the added cost.
However, I think the benefit has a lot of nuance that you may not even notice at first. I feel like it took my group 3 years before we understood the reasoning behind the added flexibility. It absolutely was not obvious at first, and I've been a Pathfinder player since it started, and this gaming group has some very smart folks in it (including a former maths teacher.) For at least a year, as game master, I couldn't understand the point of adding the player character's level to checks using proficiency, until it finally occurred to me that challenges could be rated higher than 20 or 25 or even 35. I could construct adventures and dungeons soft-locked by either level or a chance critical success, and not feel that my role as a game master ends once players reach level 10.
Obviously the cost benefit of complexity and math depends on whether your gaming group is going to use what the system offers. It's easy not to, because "good enough" is often, well, good enough. But if you feel like you want a little more room to play around in as a game master, then Pathfinder 2 offers a lot of design features that enable you to chellenge even your high-level adventurers. If you feel like you want precision dials for your characters as a player, then Pathfinder 2 offers that too (but an exponentially uglier character sheet, no question about it.) Whether you use it or not, hopefully it makes a little more sense than an apparently arbitrary decision by some designers somewhere, now that you've read this!