Does Microsoft discriminate against health care providers?

A common point of view, which applies to all small partners focusing on (very small) SMB business. It's not about the industry you're in. Like you said, it's about the customer size you're focused on.

As a large CSP Provider we've seen a lot of partners complaining against these new rules, as we did as well towards Microsoft to support our partners. Microsoft has made some changes to these requirements before, and is still improving on them (making new adjustments as recent as last week). But I doubt Microsoft is not going to change the >10 seat requirements anytime soon for MWP business. Their focus is just not there for the <10 customers.
You could also see this as an upsell enforcement. To get those customers from 7.5 seats to >10 seats, by selling other workloads as well.

Regardless of what we think, these are the rules we need to play with..

Of course, while you might not be eligible for the new Partner Designation status anymore, you should still be able to renew your old Silver or Gold Competency Benefits. Or as an alternative, purchase the Partner Benefit Packages which include a lot of IUR licenses for partners to use.
Yes, with both options you don't actually have a partner status anymore. But at least you can still get most of the benefits from them.

Unfortunately I don't have answer, but hope I gave you some insights.

Cheers,
Martijn