I've found having it all in a single html file tends to makes it easy to survive on a lot of different kinds of networks, and I like that the larger context of the site is automatically attached to any particular part of it (which is invaluable for my work). To my eyes, it's what a PDF dreams it could be.
Also, the ability to download & email the one file that is everything it is invaluable.
Never have to worry about the editing environment when porting from one machine to another. Never have to worry about version compatibility and stuff like that.
HTML+JS are mature enough that we can reliably expect the software required to open and edit your notes (i.e., a web browser) to reliably exist in the future. Can't say the same about most other formats.
Even LaTeX, with its version-control-friendly text file format, very quickly runs into portability issues with package management. Someone gives you a .tex file - good luck trying to compile it without Internet connection.
I've found having it all in a single html file tends to makes it easy to survive on a lot of different kinds of networks, and I like that the larger context of the site is automatically attached to any particular part of it (which is invaluable for my work). To my eyes, it's what a PDF dreams it could be.