Because new tabs are placed to the right of the tab they were opened from and new tabs opened from the new tab button are the on furthest right, it means that tabs further to the left are probably older, and therefore more likely to no longer be needed. I think it would be good to have a “close tabs to the left” button along with the one for closing tabs to the right. What are your thoughts?
Yep, looks like there’s one here:
https://addons.mozilla.org/en-US/firefox/addon/close-tabs-left/