For many newcomers starting out, the Rails CRUD generators are good enough to generate their entire admin area. And Rails comes with sane security defaults.

I agree that GraphQL + React will be pretty and work well. But for one-man start-ups, the focus is usually on "looks good enough and kinda works".

So I believe I'd go with Bootstrap & Glyphicons, just to get results faster.

Hasura outperforms Rails by an order of magnitude in addition to being faster to develop with. Supabase also looks really nice.

This man knows the way.

I use this stack and I'm pretty sure I could pump out any SaaS business in about two weeks with it. Host on Heroku, use whatever analytics system you want.