I question this as well. But the level of general skill has gone down in LoL. As abilities become simpler and damage amplifies, hard to wield champions become out of favor for ones who aren't. Not getting into the OTP situation. But as a generalization and meta, some champions are played merely for their weekly OP status per patch number.
Runes and masteries were at one point a level of player choice which could potentially indicate skill. They simplified that. So most options are more damage. But what they should really do is kick most the damage out and find other new unique runes and keystones that help more of the older and outdated champions. Th runes did some things with movement speed, cool downs, and gold income and some with health regeneration or tankiness. But really even then, most of it is a form of damage. Grasp has damage, Aftershock has damage. I've never seen guardian once used. Demolish has tower damage and chrysalis gives damage.
Not to even mention you get damage depending on your primary + secondary trees. >.>
But I think the damage creep is because Riot, wants a more aggressive player base. They don't like tank items unless they do some kind of damage. Titantic Hydra, Sunfire Cape, Deadman's plate, Sterak's, Frozen Mallet, Abbysal, compared to Warmogs and Spirit Visage which don't really do much for damage besides a health stack w/ T. Hydra.
By aggressive games, we get shorter and faster games. You get a snowball effect. They want clear winners. None of this stalement crap for 45+ mins. You got dragons, rift heralds and barons to help end the game quicker.
Shorter games probably mean less bandwidth which means the game is cheaper to sustain in general. Imagine a year ago all global players having an average game of 30 mins. Now imagine the same player base doing it for 25 mins. Then 20 mins. That means less up time on the servers. Less bandwidth used.---
In all honesty.
Probably the faster the game gets, the more money they save. But realistically they can only go so far without losing their player base completely. Even if some are already leaving. They have a steady grip on the LoL community. It's a bit global. They have fun champions and fun skins. "It's free.", even when its a highly addictive game that many have poured countless of dollars into. To some its a drug. They burn 10+ hrs into it a day. Streamers love it and hate it. They are getting rich for playing something they are addicted to.
And Riot likes that addiction. It knows we pay well.
You think of games like smite. Where you can just buy every champion. LoL still doesn't have that. Because selling them 1 by 1 is more profitable. As most players don't have the patience for their impulsive nature and buy digital goods that aren't lasting. All those skins and champions can be updated and reworked, re-visualized into something you might not like.
Fiora's hair. Warwicks new 'spike'.... I can only use the Hyena skin now because it looks like a engine coming out of his back and Mad Maxx-ish. His other skins now all blow. Which is merely my opinion.
Either way, it probably comes down to profit and cutting corners in the name of keeping the game 'fresh' and exciting.
Because if they really cared about players. They still have dominion, urf, hexakill, etc etc. Game modes should just be there for players to play and have fun with. But LoL isn't about the 'fun' of the game. It's about the 'profit' of the game.
Even the 'crafting' system is like loot boxes and micro transactions. Because its known loot boxes can make a lot of money with very little in return due to the 'RNG' of it all.
Like if Riot cared about its players, they have like Mastery '10' skins. You get a free skin when you hit mastery '10' of a champion. Perhaps even if it was just a mastery skin. But imagine if each champion had a mastery skin.
Either way. Money probably has something to do with the equation of more damage in LoL even when its against the thoughts and voice of the community.