I'm not a fan of it but I also appreciate the younger generation coming into first time buying for their first home may not have much choice, seeing as house prices have climbed significantly higher rate than wages. So they're stuck.
The issue is no different in many ways than a business partnership, if you go into house shared ownership with someone and then you fall out (like a divorce).
I also don't like it morally when the shared ownership provider is a property developer, they're getting two bites at the cherry and I'd argue profiteering on the vulnerable and those unable to get onto the property ladder because of how screwed up property prices are.