I think the other big thing that killed in game cheats and debug screens was Xbox and Steam Achievements/PlayStation Trophies. Some of the "value" in such tokens of game completion are the "skill checks" it takes to complete them. If a game provides cheats inside of it, it either needs to disable those Achievement systems, or it loses the ability to unlock them, and that's platform enforced by Xbox/Steam/PlayStation. So it's easier for most games to just not include cheats so they don't have to worry about accidentally violating platform terms on Xbox/Steam/PlayStation should players discover and "abuse" the cheat systems.

Similarly PC games with mod support often have to disable Achievement systems as soon as any mod is installed just in case the mod happens to offer cheats. Which also seems to have impacted mod culture to some extent with entire classes of gamers not installing mods ever to make sure that they still win Achievements.

It's an interesting social dynamic and I think one of the clearest lines in the sand for when cheat codes disappeared, especially in genres like the FPS where "God Mode" and "noclip" codes were genre staples until Achievements. (Because DOOM offered them, every FPS offered them. Until they stopped.)

PC games don't have to do this. Steam doesn't have a policy that achievements must prevent cheating. This is entirely a developer choice.

The main reason cheats have disappeared from mainstream games is because many of them prefer to sell them to you as micro-transactions, item pack DLCs, etc.

Steam Achievements are trivially to cheat at for most games, especially single-player like Ecco, for example via SAM.