The evolution for Old School RuneScape was to just make cheating a built-in feature. It only takes a couple clicks every ten minutes to "play" the game.

I don't think you are wrong, per se, but at the same time the skill level of late-game (or even mid-game) encounters has also been increasing. Plus, they usually aim to strike a balance between less intensive but also less efficient activities vs. the ones requiring frequent clicks and full attention but offering quicker progression.

Only if you're talking about the Gemstone Crab.

Which was added because people were already doing that on the normal crabs, but fighting over the spots. So they made a crab that any number of people can fight at the same time (combat is ordinarily one to one), and it always lives for ten minutes no matter how many people are fighting it or how hard.

this was the evolution of most online games, same reason why every action/shooter game that's online at the moment has a mechanic that allows players to see through walls : if players have that mechanic available to them then there is a likely scapegoat to believe killed you rather than realizing that it's a hacker with invisible textures or wall hacks; lessens the work for the developer answering hate mail from people that got killed by hackers.