I work for a company where we basically sell access to a SaaS behind a frontend powered by React. The customers pay, very well as I'm led to believe by our figures. There's no advertising. Nobody cares that the frontend is slow, because that slowness is because it's an SPA and that's factored in as a necessary cost of business.

In other words, even if you pay, there's no reason to think the software should be any better.