The best website I use is an explorer, not an editor.
Yes, and it's GitHub. GitHub is an explorer and a search engine for the git protocol, and so most of the data I submit to it or edit is replicated locally. I edit most of my work on my computer's command line - but GitHub is often useful when navigating to bits of code "far away" from my command line's cursor. It has a slightly nicer syntax highlighting, a fantastic internal search, and an integration with a search engine like Google.
Given that git isn't opinionated about the editor I use to write texts or manipulate my Unix-based file system, I've optimized my workflow by using a pro tool called vim - a special text editor. But I use a flurry of other Unix tools too, and they're all well-documented, free of charge, and non-proprietary.
Also, they don't track me. They're generally rather secure and aren't targeted for cyber attacks as much as consumer apps are. Files are a beautiful and versatile abstraction and integrate well with git, my operating system, and GitHub.
Most importantly, by voluntarily opting into GitHub's features besides their git remote hosting, I can customize my user interfaces to a very high degree. See, having to work many hours a day with GitHub and git, I've found that even slight flaws or mismatches in the user interface I use for working can significantly impact my mental health. So having the freedom to customize, style, and use the tools I prefer to manipulate the fundamental data structure on GitHub is, in my opinion, the key to why people like me love to use it.
And I would like to generalize this further than GitHub and say that I also use other websites where this metaphor for interaction is executed, where the website is merely a collection of "immutable" documents and is meant to explore and not to edit.
It's because editing and manipulating on the web is so painful. Website state can be lost, there are many rendering issues, and website structures sometimes get re-rendered under my cursor; login state is fragile, and I'm being tracked and observed everywhere by giant global corporations stealing my data to enrich themselves and their shareholders.
The best websites I use are explorers and not editors.