So what’s preventing those people from using bookmarks as “check this out later” tool?
Bookmarking a page does not give you control over its content. So if you bookmark something and the host deletes it, you are screwed.
If you instead clip the content or save it as a PDF, you retain access regardless of the original host.
For example, I save every good article I read as a PDF, which I cloud sync to a folder. I have a second folder for stuff I don’t want to keep open as a tab but still want to read later. There are probably far better services out there, but I like the lack of technical dependencies and lock-in.