EU referendum, brexit and the aftermath

I'm interested to know, in reference to issues brought up in this article, what's stopping us recognising EU regulations and statuses, even if they're not reciprocated?

This hinges on something called 'mutual recognition of professional
qualifications'. If there's a deal, the qualification you have in
Europe entitles you to work in the UK and vice versa. If there isn't,
all that falls down.

What's stopping the UK recognising EU based professional qualifications, even if not reciprocated?