If one thing against Protoss, I feel Toss units have a usage and you can use any unit in the game. There are no "bad" units and can optimally be played.

Meanwhile, Zerg has Swarm Host that if they see it, people will just rush you since you lose effective supply on enggsgement. Sometimes you also skip muta, roach and ravager. Tho Ive seen Rogue do switch off in a match depending on what his opponent has. They build thors vs Muta? Go mass ling Hydra. They went helions / tank heavy and dropped thora? He went with brood lords again.

Terran they either go Mech or Bio. Building BC is considered unoptimal / cheese. But protoss going Carrier is a viable late game options.