I did not say "10 years ago". I said "10 years".
Yeah, all of that is accurate. Everything's changed in 10 years, or at least basically everything has.
At the same time...That's 10 years of code. Not code from 10 years ago, 10 years of it. 10 years, not 1 year that was 10 years ago.
Overall, that adds up to more than live. Once you add everything up, it'd take more time to re-create each thing from the past 10 years than to remake the entire live game from the ground up.
It doesn't matter that there's more people - There's still 10 fucking years of shit. Because, yeah, that's also 10 years of art. They could dig up the splash arts from the wiki, probably, but all of the goddamn models and effects and shit would also have to be re-created.
Sure, I don't code. I barely know anything about coding. At the same time, I realize that there's been a lot of shit in 10 years. And you can't just revert to a specific patch (which would be significantly less code), because you're going to leave a lot of people pissed because "Wtf Riot that patch was shit why not revert to !?!?!?!?" from 90% of people.