Back in the day in say, Season 3, doing something like 25k+ damage to enemy champs was like a game where you were absolutely fed and massacred the enemy team.
Now, you walk out of a game with 30k damage to enemy champ easy, and a situation where you were absolutely fed you'd be looking at something like 60 to even 80k damage on enemy champion (on rare occasions, it can even hit 100k but I'd only seen that on 1 Xerath once; remember, that's not total damage but damage dealt on enemy champion).
Looking over to tanks. Any reasonably fed full tank can end the game with about 70k-100k damage absorbed from damage taken and self-mitigated damage combined in today's meta (and if you think those numbers are absurdly high, you know where to look at). That's a lot! Guess what, they still melt like butter anyway because resistance doesn't mean shit and damage is over the chart. So that extreme damage absorb isn't so much about them actually tanking that much but more that they got melted by absurdly high burst damage the moment the enemy showed up and they instantly died to overkill.
Damage creeping is certainly real.