It's certainly been an effective tactic and I'd caution you that I don't think the examples you use are counting these people as customers per se but more as trying to solve issues related to two-sided marketplaces.

These businesses are trying to prove their worth as effective lead-gen tools for the practitioners. The service providers are more likely to be responsive/pay-attention to an email or inbound message that says "We have someone interested in booking with you" than "Hi, I'm calling from Company X, would you please-sign up and maybe we'll get you some customers?"

There's no implied endorsement and the data is really "directory" type content, so it would be unusual to find someone unhappy that their business profile is being published.

So it's absolutely a valid tactic but it's also a case of "devil is in the details." Happy to talk through the specifics of your inquiry and what you're looking to do in a call with you.