I personally never felt that tier sets made my classes feel playable I think they just made them feel more enjoyable. It’s absolutely true that tier sets were a requirement to be competitive in terms of instanced content, but I may have also just been lucky to not have played bad specs where tier sets were required for a spec to feel playable.
MM hunter without In the Rhythm for the massive haste and Focused Fire for the Focus regen feels extremely slow mostly because the spec itself is so reliant on just Aimed Shot instead of having its damage a bit more spread across different abilities.
I prefer corruption tho, it’s more fun than azerite armor, TD in bear form is just fun, I’m doing well in epic battleground even though I have no idea how that spec works.