ISTM housing costs are the big barrier for Boston? Tech companies already know the area has plenty of talent.

Expensive housing can be a difficult problem, since lots of vested interests are opposed to any effective solution.

I think the reason the Boston is not more of a tech center is that MA law supports no compete clauses as condition for employment. CA has high housing prices where the tech industry is located. However, CA does not support no compete clauses for condition for employment.

There are definitely a lot of factors at play (education, etc. etc.), including a preferential attachment model where cities with established startups and funding opportunities will attract new startups.

You've really hit the nail on the head, however, as that no-compete clause is, while perhaps even enticing to large companies, very restrictive to new startups. We seem to disproportionately have ideas about and go on some entrepreneurial mission in an area we already know intimately, usually related to our current employment. No-compete clauses destroy that entire basket of opportunities.

That seems like a reason that no state besides California would have lots of startups? We're moving the goal posts a bit, however, since thread parent from Boston cares about tech jobs which is not the same as startups.