In my experience, at least with startups, non compete agreements are often pushed and drafted by the legal team of the entities investing in the business.

Investors want to be protected and their attorneys will do anything that's necessary to make sure there aren't loopholes left open for ideas to be stolen.

The result is poorly drafted and ridiculously broad non compete clauses that would not be enforceable in most if not all states.

However even when they may not be enforceable (and you will hear the hiring manager saying that 100 times), non competes can still hurt candidates big time once they go back to the job market because many companies actually have provisions to disqualify those coming in with the extra baggage of a non compete.

If candidate A and B have very similar skills and experience and A has a non compete and B doesn't, why would anyone bother with A?

So it is true, non competes are in most cases non enforceable but they can still reduce your chances of getting a (better) job.

I declined offers after months of negotiations because of non competes and I would advise others to refuse to sign them, unless you desperately need the job, the compensation package is amazing or there are provisions or amendments to the clause, like a reasonable garden leave, that compensates you for having to carry a stinky non compete agreement on your forehead for an entire year or more if things don't work out.

If they want the non compete, make them pay for it, don't pick up the tab yourself.