Why do browsers allow users to open more tabs than it is possible to manage for a good user experience?

It is not unusual these days to see someone on a browser application with so many tabs open that you can't even see the favicon. I remember when bookmarks were provided to help manage a large number of webpages that users want to come back to but I don't really understand the user behaviour that the browsers are supporting by allowing so many tabs to remain open with no real way of managing or navigating through it easily.

It seems like in many instances the user is just following some trail and leaving the tabs there to come back to later, but over time it gets cluttered and they are probably not even able to retrace the steps back to the tab(s) that they want logically.

Is this catering for a typical web browsing behaviour or an unintended consequence of browser performance improvements or is there another explanation?