Experience inflation often comes as a means to prevent low level interactions from being as effective for leveling up.
CRPG's often don't have scaling values on things as you level up (I.e. A level 1 enemy killed while at level 1 giving 100 experience. While the same enemy killed at level 10 granting only 1 experience), so instead they just inflate higher level rewards to provide the same effect of reducing the relevance of "Low level" actions.
Personally, I think the entire "Experience" concept is a bit dated in CRPG's. Especially in the way that it ends up stifling freedom by making you have to interact with everything in order to not be underleveled (Which can be highly detrimental to actually role playing... Like, my "Evil" character has to save every cat from up trees and make nice with every NPC regardless of however stupid their request is because I need the experience... Or conversely, my "Good" character has to be a mass murderer because I need to do every combat because experience)
I quite like the popular Tabletop implementation of "Experience" whereby you simply gain levels from reaching specific milestones in the main story. Meaning you can do as much or as little side content as you wish and interact with it in however you wish (Do you kill everyone? Do you talk your way out of combat? Do you talk your way out of combat but kill everyone anyway? Do you stealth past it? Do you find an alternate route and simply avoid it? Do you find a non-combat method of eliminating enemies (Like poisoning their food/drink)?)
The only crux of levels as main story milestones, is providing side quests with enticing rewards to get people to want to do them (Which can be done via money (So long as it has actual worth in the game, without you amassing thousands of gold naturally), items and story impacts)
In regards to stat inflation, that is normally a byproduct of longevity.
I.e. If you go through 1,000 hours of progression, even getting a +1 damage bonus per hour is going to have you dealing 1000x your starting damage.
This is what lead to D3's ridiculous scaling. Many years and additional Torment levels of progression, leading to skills needing 20,000x damage bonuses to even be considered (And even then being quite weak unless further amplified)
The longer that progression lasts for, the higher the scaling ends up being as you have to do more incremental increases. This is exacerbated by how much those increments span. Often times people don't find it exciting to just get a +1 bonus per progression, they like getting more substantial jumps like +5, +10 etc. Something that makes them feel like they've progressed immediately even if ultimately the many small increments added up.
This is actually something that happened in Cyberpunk 2077. Originally the game had a perk tree full of stuff like "+1% damage with pistols". Which many people complained about feeling too "Low impact" when in reality the many increments of 1% damage meant that you started off doing 40 damage per shot but by the end of the game you were hitting for over 1 million. So they reworked the system to what it currently has, where perks feel more immediately impactful but there are FAR less damage increments, so people feel good when they unlock a new perk but they don't scale nearly as much.
