complex dashboards like CircleCI or client portals like maybe your bank or health insurance portal

many pages and lots of functionality with lots of data floating around like Reddit, Twitter

literally everything/anything like Facebook, GitHub, etc

For simple apps, I'd go with a PWA if possible. For single, mostly informational, pages you usually just need a static site. For a company blog, some of these tools could be used to make the frontend for a CMS, but you can also just get away with Wordpress, Squarespace, etc most of the time unless they want some really custom functionality. Then there's also micro-frontends and Astro and other related tools if you're trying to do a lot of different things and wanna mix and match different solutions to different problems