I'm not very optimistic about the technical direction of Mastodon. Mastodon had a minimal HTML-only interface before, you could read posts and replies of each profile. They removed it some time ago, now you just see a blank page if you don't have JS, and I think it's a huge mistake; it was a clear albeit small advantage over mainstream social networks.
A truly overwhelming majority of users browse with JS enabled. Designing or even considering those who don't is (in the most literal way possible) a waste of time.
A good designed web app works just with plain html and minimal ressource use and than adds on top of that the get even better with css and js niceties. This used to be called progressive enhancement, if the client supports a feature, make your website better for these clients. It's just better and well rounded design with the added bonus of supporting clients with less capabilities.