That's the usual case when vid3o g4mes are "CPU limited". One has to just look whether the game does anything high-level that other games didn't do 10 years ago. Reasonable hardware limitations related to the CPU have normally to do with complex physics effects or unusually large crowds of NPCs. (Many games are CPU limited even for fairly small crowds because their engine isn't optimized for that purpose.)

I mean, to some extent maybe.

A surprising number of video games have at least one 'master switch' statement for at least one important aspect of the game logic that has to evaluate on a single thread to maintain some level of 'coherency' while operating at any given frame rate.

The challenge with using threads without careful control of or understanding of the underlying system hardware is that you can wind up with various quirks (Every computer I had from 2000-2010 had this weird 'judder' with HL/TFC/HL2 and explosions, didn't matter the sound card type, CPU brand, or Video card brand,) at best or a rats nest of logic bugs at worst (i.e. the pains of coding multithreading.)