Tbh, all these solutions are yellow paint in a different coat.
Wanna guide the player through a path? Have a guide NPC go before you (might even be the villain in a chase sequence!).
So now I have to tag behind an NPC that runs at 75% of my speed, because if I lose them the whole concept falls apart, so I have to bumble around behind them? No thanks. Or if it's a villain, the whole immersion breaks after I realize the villain doesn't actually run off if I don't follow, but instead just waits at the next corner for me to catch up.
Want to clearly show in which places you can do X thing? Have a clear visually distinct asset that stands out mark those places. Make sure you don’t have similar assets elsewhere.
So the yellow paint is a yellow asset? Or a slightly less yellow asset? It's the identical thing, just a little less visible. That was OK for Wii games and before that, because anything that deserved its own asset was interactible. There's a plain wall with a 16 polygon cube on it, well of course this is an interactible button. Now do the same on a highly-detailed wall with bumps, groves, wood supports and so on.
If the argument is accessibility, just make it an option to turn those special assets bright pink/yellow, or just a much more distinct (even if visually unappealing) asset for higher-budget games.
So yeah, that's just yellow paint in 3D.
Wanna show which ledges are grabbable? This may be the only acceptable use case. But even then, there are more discrete ways like shining stones or have the character extend its arm towards it or something. Or just make basically every ledge grabbable. I had no issues in either sm64 nor in the original assassins creed, and neither had yellow paint.
Assassins creed didn't have to show you what's grabbable, because everything was grabbable. You could literally run up to any random wall and the player character would climb it.
SM64 falls in the "16 polygons per wall" category.