You probably didn't play "old League".
The vast majority of these opinions seem to pour in from players who started between the very end of Season 4 and Season 6. That era of the game comprises two well established tank metas that, to players who started before the tail end of Season 4, were "low damage" and generally slow.
Before that, overall damage was around the same as the current day (and in the case of a few champions, much higher).
What you're misunderstanding as an excess amount damage is actually an excess amount of damage _in the wrong places_. Had you told a Season 3 player that there was going to be a support with an AOE Darius ult that was also an execute and granted full kill gold to allies _or_ double kill gold to the user, they'd have laughed at you.
Because that's asinine.
The more supports complained about feeling irrelevant, the more gold they were given, and the more they were offered damage alternatives.
The more tanks complained about feeling irrelevant, the more damage was added to their kits.
The inherent issue with this is that it fed into the idea that tanks and supports could only be relevant by _dealing more damage_, when that isn't the case. Those changes catered to sub-par players who had no understanding of the actual roles their class was supposed to fill. Now fast forward and everyone is one shotting, even when its not healthy for a champion in their role to do so.
Years ago, tanks and supports provided a front line and utility. Effective, well balanced, and knowledgeable players understood that they didn't need absurd damage to effect the outcome of the game.
-Tanks provided crowd control and a front line.
-Supports provided utility and vision.
-ADCs provided sustained, ranged damage and siege.
-Assassins provided mobile, single target burst damage.
-Mages provided ranged, high AOE damage.
-Burst Mages provided a mix between Assassins and Mages.
-Bruisers provided a mix between Assassins and Tanks.
Everyone had a role and it wasn't just "I can't feel impactful or have fun without doing more damage".
If you think Assassins from Season 9 are a problem, then you _do not_ want "old League", you want "League Dark Ages Tank Meta". Season 2/3 Assassins killed you before you could throw up your barrier. Zed didn't one shot you in a team fight. He erased you from the game and wiped any trace of the two guys unfortunate enough to have been standing next to you off of the face of the Earth. Kha'Zix's isolated Q did 2,000+ damage. If you were an ADC, there was a good chance it just killed you. Rengar leaped from stealth and just killed you in one second. Always. Not just when he was at fifteen kills, _always_. Kassadin was the biggest atrocity the game has ever seen, making Season 8 Irelia and Akali look like scared little animals. And he had a silence. Talon did the same damage he does now, but had a blink instead of a jump, that also silenced the target.
As for Mages? Veigar's R scaled with _his_ AP and _your_ AP. Someone picked Veigar into your Lux? Too bad, you die in one ability. Oh, and also you don't get a cheap rune that gives you a massive resistance buff. Hope you didn't plan on enjoying this game, but serves you right for picking an AP mid with Veigar open. God forbid you have to play against AP Cho'Gath with his two second silence that hits you _if you were standing in the indicator when he cast it, regardless of where you are now_ and his significantly higher damage scales that deleted any standard mid in one rotation.
ADCs? Phreak was famously ridiculed when he responded to the question "how do I beat Vayne?" with "2v1 her, dancing in and out of vision so she can't stack her passive". 2v1 her.
Renekton was so oppressive that Riot coined the term "The Renekton Bar" for their new champion balance philosophy. Meaning that, instead of nerfing the over the top murder machine that was Renekton, they would buff other champions to stand up to his level. This came after Jax was reworked for being, as Riot put it, "a ball of stats", the likes of which was not healthy for the game.
Now every role has been skewed beyond proper identification. The majority of post Season 5 players don't even know what a Burst Mage is and call them all "Assassins". They've never even heard of roles like "Anti-Carry" or "Pusher". Tanks, bruisers, and some unlucky Assassins were thrown into the blender that was the "Juggernaut rework", creating a vile class of champions that don't take enough damage and do to much damage for how little they take.
It's okay to like tank meta, but don't call it "old League". Don't spam post about how "it's a totally different game than it used to be because everyone one shots each other".
If you want to know what old League really was, then go watch some videos of the game between Seasons 1 and 3. If you like what you see (the defined roles that had specific jobs and didn't constantly mix into a grey blob of no position identity), then what you should be asking for is damage to be returned to where it belongs. Not on tanks and supports.
If you don't like that, that's fine too. But make it clear that you want "tank meta", not "the old game back". You want slow paced matches with high damage mitigation and a greater opportunity for comebacks. Longer games, less high stakes combat in the early/mid game, more forgiveness for mistakes.