You can think about this as a method for the SaaS company to look bigger and have more customers then they actually have.
There are many companies using this tactic.
ie: http://opencare.com/ , http://www.zocdoc.com/primary-care-doctors/niagara-falls-252187pm
There are so many companies like this that seem to populate their systems with companies which are not their customers.
Is this a valid tactic? I have seen small businesses complaining that these type of companies are using their company name/log/etc without there consent.
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.
IT'S A DISTRACTION...
Instead of pretending that you are more awesome than you really are -- just be a little bit more awesome.
BTW, that mantra works for more than just client acquisition. It's a badass roadmap for treating your employees better, designing your web presence, or engaging on social marketing platforms.
JUST BE BADASS. Don't try to copy someone else's half-ass, poser bullshit. Wake up in the morning and ask yourself: "What can we do today that will blow our client's mind?"
And then go do that shit.
You make some valid points.