I agree, I think it's unfortunate when services get shut down post acquisition.

I also agree with you that all startups should have a clear path to monetization. I would assume that institutional investors would require as much before investing, but I think that would probably be assuming too much these days.

However, I don't think that all startups should "turn on" the monetization immediately. For those us trying to build two-sided platforms, we need to get one side of the platform on first. Typically this will be the users as brands and retailers are still very much focused on reach and are very slow to make decisions.