I was blown away by how polished it was once I finally tried it a few months ago. I set up auto-deploy on push to Github + build command in like two clicks for all of my projects and never looked back.
Their free tier is probably too generous though. I know someone running the biggest website in a massive niche and they are serving their SPA for free from Netlify.
Their free tier has a 100GB/month bandwidth cap — surely the most trafficked websites in the world would very quickly hit that limit, no?
Your point stands nonetheless — they could certainly be losing money on certain large users of their free tier. Serving relatively static content has gotten extremely cheap across the board, though, and like the parent said, they might be benefiting from the pricing by more indirect means.
Their free tier is probably too generous though. I know someone running the biggest website in a massive niche and they are serving their SPA for free from Netlify.