So like, in theory, yes, but in practice, now everyone has to take Adderall just to be able to keep up with their coworkers.

Would you apply the same reasoning to caffeine and nicotine? Should we ban both? You're also seeing the world as a competition between people ("keep up with their coworkers") but I believe most people are actually trying to make a living (no need to take adderall if you are already satisfied with what you have).

Seems like the free market at work to me.

That's about the shortest, but most on-point and total, take down of the free market I've seen in some time.

It's straightforward/trivial to excel over coworkers (even those on stimulants) at most jobs.

Regardless, this idea that one needs to "keep up", as if work were a competitive footrace, is something you have invented.

Not at all, there's more work than can possibly be done. It's not a sports competition - everyone can win.