Riot's philosophy of Damage = Fun can actually be tracked down to earlier more balanced seasons. Their reasoning for way back in the tank meta, just in one example, a full armor/health rammus doing half a squishies health (that was actually alot of damage back then) with one combo: Damage = Fun.
In other words they made tanks do a disproportionately unfair amount of damage, even ones that don't build any damage items whatsoever, because less people would play tank designed champions that are just damage soakers/cc bots. Can that not simply be what tanks are instead of needing a now 2000 true damage ult? (Cho'gath)
History of just a few meta solutions Rito has had over my long time with this game:
Mages too weak? Introduce CDR items and runes so that they can constantly spam their abilities and put out more damage (at which point timing ult cooldowns to strategize around became practically irrelevant, now you just use ult, back, get in lane and ult is probably back up again).
Games too long? Increased damage towards towers!
Tanks too strong? Increase damage with increased armor pen/magic pen, and later even more with true damage.
ADC's too strong now? We'll nerf crit, essentially INCREASING EARLY GAME DAMAGE (which is now the whole game btw) by making only lethality, high early game damage strategies viable.
Edit: I should say I do have fun still in the game, but mostly just in the first 10 minutes trying to beat my lane opponent. By about 15 minutes it is very obvious whether we're absolutely stomping them or getting absolutely stomped. Absolutely stomping an opponent that I know just can't come back isn't that satisfying, and getting absolutely stomped is a terrible experience right now because you just can't come back.