The problem in League isn't damage creep and has never been damage creep.
If anything, it's been sustain.
Think about it this way, if damage just kept getting higher and higher, why would we play tanks at all? We'd just be picking assassins and running from place to place with little to no thought whatsoever because if everything has damage the most effective champions are the ones that gapclose you the most easily. On top of that, there'd be significant changes in DPS.
There hasn't really been. Another high elo poster posted DPS charts over the seasons and ADCs have been dealing roughly the same damage consistently for seasons.
So what happened? Sustain has been buffed and buffed. Enchanters got Windspeaker's, +%shield/heal power, redemption, locket got buffed, etc. ADC items and masteries have received a good chunk of sustain or received new items that add to this as well. Death's Dance was added, Bloodthirster went from 12% lifesteal -> 18% after 30 stacks to straight 20% with an overheal, Fleet Footwork was added, and Mercurial Scimitar gives lifesteal.
This hurts burst the most, since especially very early on burst is almost capable of killing you. Add in a couple of these sustain options, especially with the new delays on burst combos, and it makes burst have significantly fewer opportunities to kill you. Especially against bruisers who itemize to be barely able to 100-0 you, it makes them downright difficult to use in most scenarios in which the ADC is next to his support.
And while this does make it harder for DPS champions to kill you in theory, what's gonna happen? Vayne needs another auto to kill you? Stop the presses. This is also why mid meta is particularly fucked in pro play. You have to play as Taliyah, Cassio, Ryze, Azir, Galio, or Swain. 1 of those champions is a roaming tank (Galio) and the rest are DPS champs. 2 are tanky frontline DPS (Swain/Ryze), one is a playmaker DPS (Azir), one is lane kingdom DPS (Cassio), and the last is a roaming DPS (Taliyah).
tl;dr stop making healthbars do the WoW thing where they go up and down a slider like an indecisive person trying to adjust their facial features on Skyrim.
EDIT: I posted the dps chart in a later reply but I don't think people wanna dig through responses so here it is.
is only viable because adcs get enough sustain from fleet footwork and ardent censer. Tack on the insane regeneration from red buff later in the game and many adcs opt out of lifesteal altogether in favor of crit, significantly increasing their overall damage and reliability.
and
exist, I think the biggest problem is people who refuse to buy them on champs that don't have a lot of burst.