Yes! Personally, I think it's very exciting, just as you said. In my estimation two of the key components are a database, and user management. Lite Engine has a User API the gist being it allows users to signup to your service, Lite Engine handles sending email signup confirmations (ie click this link to confirm your registration), and handle password changes and resets, also via email. A user of my service can configure their own SMTP, or I'll send X number of emails a day on their behalf. Then users of your service can login, and perform actions based on the permissions you assign. So you know, a forum, ticketing system, whatever, as SPA's are possible. I have forum demo I'm working on that exercises all these features.
So, you could use a service like netlify, neocities, or even github pages to host your HTML, CSS, and javascript, and make CORS calls to lite-engine.com for the backend. Single page apps with no server. I think it's possible with Firebase, but I don't see anyone doing it, and I personally prefer to work with SQL for larger systems, I'm betting others do as well.