To name a few, I interact with a number of sites on shared hosting that have been using FTP for years. I also work with a data server that primarily interfaces with its data store through FTP. It also used to be easier to just host an FTP server and manage its access independent of a website, but still link to it in a browser where people who are not technically inclined could browse and interact with files without needing a separate dedicated client. Even for me, it would be simpler to just see an FTP file listing in a browser sometimes
The point is that browsers used to be able to browse the Internet, but major players such as Google have been working hard to limit all of these things to just HTTPS. Excusing things away by saying "well I don't use it, so it's useless" has only helped to narrow this path
Netscape used to come with a browser, a mail client, a newsreader, an HTML editor.
We've moved beyond that now, why worry about a browser being able to read Gopherspace or Gemini pages? Putting those into dedicated browsers of their own has been the perceived action for some time.
The reason is to connect them together in one experiential flow. That was the purpose of hypermedia, the interconnection of platforms and data sources.
People aren't doing that, I realize it, but maybe we should fix that instead of abandon the dream.
All of those things center around the same set of technologies. Browsers today even come bundled with developer tools which still include HTML editors. But it's better for there to be two separate applications that both use separate copies of the same rendering engines and UI chrome? We might as well just make everything in Electron
Also, it's not like browsers are any less complicated now. They support things like 3D rendering and even MIDI device interfacing which are arguably more complicated for less benefit than supporting alternate protocols and technologies