There is absolutely no technical reason why bookmarks and tabs are separate concepts: if there is a way to search and organize bookmarks more easily that should be applied to tabs, and the idea that a tab has to be some kind of constantly-open running program burning RAM and CPU is essentially a mistake made only by Google (and we can probably guess why they like that), as the only permanent state of a tab is the history of URLs it represented (which can be easily verified by rebooting: if the browser doesn't save it to disk it isn't part of the semantic state).