If you told me that was the case today with web developers generally, I’d laugh at you even harder than I would have if you made that prediction ten years ago.
Similarly, a function that accepts (explicitly) `A | B | (C & D)` and then dispatches to functions that accept `A | (C&D)` vs `B` is, you guessed it, type algebra and is a common pattern in hot paths through every TS codebase.
Just because the formal nomenclature is unknown does not mean the concepts are unfamiliar.
It's the opposite in my experience. Most web developers I work with (a lot because of consulting), specially the average "React sprint runner" doesn't have a clue about anything slightly above basic types and just google/chatgpt whenever things break so they can move on to the next task in the sprint.
cryptic typescript errors don't help here either.