Back then you could just quit the server/match if somebody was obviously cheating (or they got banned).

With competitive matchmaking cheaters can hold players hostage until the end of the match, as leaving incurs penalties and cooldowns that temporarily ban you from playing.

Because those were community servers often built around community. There weren't a lot of them either.

If admins allow cheating - people that want to play would leave the server

If live in a non-metro area, you probably have a handful of server your latency allows you to play on - getting banned would be a big suck

Now you just click "play game" and you get match with some strangers you might never play ever again with. Financially, those privately hosted servers no longer make economical sense for game publishers.

Because games were less common. If you look at community hosted servers now they commonly have more anti cheat, not less. Counterstrike with FaceIT and ESEA. Even FiveM for GTA V rolled out a custom anti cheat before it was added to the official game.

That was not my personal experience. CS and Warcraft 3 community lobbies featured rampant cheating. Way more than CS:GO and Dota 2.

Life was a bit simpler then. At that point in time the leaders also did not get millions for their wins.

I think that's a matter of opinion.

Personally I find both unacceptable: I won't play a game that requires me to install a rootkit, and I won't play a game where cheaters and bots run rampant, ruining the fun for everyone.

So hopefully there's a solution to this that doesn't require a rootkit.

You definitely don't play games, this is one of the reasons why people stop playing games.

Well no, because they ruin the online experience making people not play the game.

(in theory, GTA online has had / still has huge problems with bots and cheats but still earns the publisher hundreds of millions a year)

This is a naive take. Of course these developers already permaban cheaters. Firstly many of these games are free to play so "getting another license" is a non issue. They're doing hardware bans nowadays which are harder to avoid but not impossible.

Half the battle is detection though. If you don't detect cheaters quick enough they ruin enough games that genuine players start getting frustrated and leave. Anti cheats help with this detection.

Probably every anti cheat idea you can think of, in terms of detection, prevention and punishment, has probably already been tried by a large online multiplayer game. It is an extremely difficult problem to solve, a constant arms race.

False positives would very much hurt in that model. But returning to a small multiplayer experience with chosen friends would work: the in/out decision is local and personal.

It’s only a problem when you game with strangers.

Talking just about games, this really doesn't work with free games. Even if there is a lengthy 'lockout' period from the real game, many games have rampant and cheap accounts for sale and doing so will make the game experience worse.