unfortunately the assassin meta was a lot worse than the tank meta
there was another post that addresses the tank meta somewhere about a 5-tank team using teleport for free gold on an overwhelmed lane and actually stalling the match long enough to outtank the opposing team
the assassin meta was still worse though. You say skill carried it? champs could delete anyone as they pleased back then. why do you think katarina is a pub stomper? why do you think champs like fizz and zed and leblanc are hated and used in the lcs along with the newer, more survivable kit champions?
nowadays, people have to work with their team, not press a few buttons and watch someone explode
there are still cases of that, but it's a lot harder with the tank meta sitting around
for instance, mordekaiser against katarina in mid lane
katarina can waste her whole combo(unless she uses her ult)and deal about 20% of morde's hp because of his shield and he can punch her down with his mace, metal cloud and high damage abilities to make it where she can't feed off of the squishy mid lane typical while he trades her for an equal or better amount of damage
compare that to zed, who when not even fed can kill a 3000 hp target built tanky in under 5 seconds
assassins are supposed to kill ONE TARGET SQUISHY, not the whole team...otherwise they would be the ones called carries and we'd call the marksmen hired guns or something
for instance, katarina is excellent at killing squishy targets and dealing damage to up to 3 targets, but then we have a problem, if fed, kat can kill anyone, just like other assassins
roles:
mages are supposed to do high amounts of poke damage and typically be in a position where they take as little damage as possible(this is why mordekaiser is classified as a fighter/mage because of his low range abilities and his high shields)
marksmen are supposed to scale into late game to be able to kill any target they can focus on without interruption that can't outtank them
assassins: supposed to kill ONE HIGH PRIORITY TARGET
tanks: deal large amounts of damage, move slow, deal crowd control, take lots of punishment in place of the high priority target teammates
fighters: get into close range to deal large amounts of damage, potential crowd control, and function as an off tank (hence mordekaiser)
supports: supposed to bring an ability or kit mechanic that provides utility to the team or kills to feed their carry. this is why supports are frequently tank characters such as blitzcrank, thresh, nautilus, leona, etc
going through this list, why do you want it to become where 5/6 roles mean nothing to the team composition when the "assassin" could play much better?
imagine a team composed of master yi, rengar, katarina, malzahar, and nocturne
sure their kits are exciting, but it's kind of boring when one person can or has to do everything or the match is entirely onesided or the teams are virtually identical
the tank meta came around to counter these rampant assassins because they could stop them from murdering everyone on the team
it literally became a requirement...
