Why do we need bookmarks when we have softlinks. They are the same concept, and an OS that makes a distinction, is a faulty OS, IMHO.
Ditto for tabs. The task bar already serves that. It't the task bar's flaw if it isn't hierarchic.
And actually, a directory already solves that too. Which even exists on Linux. (/proc)
All you need, is a (filtered?) horizontal directory tree listing for the tasks/tabs and a sidebar with another directory that you can put softlink URL into.
Add a bit of window manager placement automation, and you got your browser.
And with JS, as a former pioneer web developer: A website whose HTML relies on a certain way of being presented or a certain interactive logic, is a defective website, full stop.
The whole point of HTML, is that it is semantic markup, and semantic ONLY!
E.g. an audio browser must work just as fine with a website. If one’s website fails at that, it’s because of disinfomatiom spread by the What(TF)WG and because of incompetence, and the causing people must be fired.