Yep, nobody enjoyed playing through Half Life 1/2, or FEAR or Deus Ex, or the early Medal of Honor or Call of Duty campaigns, or the Doom series or Battlefield Bad Company or the Wolfenstein Series.

Just because most modern popular FPSs are basically cartoony tf2/overwatch clones/derivatives and there are a lot if highly competitive multiplayer FPSs doesnt mean theres no market for a single player FPS.

It means that making a single player FPS game these days is apparently too hard modern game devs to figure out how to do.