I don't think having a lot of tabs open is a contrived use case. I have over a hundred tabs open in Firefox, and that's been pretty standard for me for at least a year.
That's me. Tabs are for short term stuff I want to check out, bookmarks for saving potentially useful/interesting stuff for the future.
Since Firefox now only reloads tabs on demand after a restart, it's not resource-heavy to keep many tabs open if one occasionally restarts the browser.
I use it the same way but it was bugging me so I installed an add-on called TooManyTabs and you can set a limit to the amount of tabs you can have opened.
I also reserve some time to clean them up about once a week, I start with the oldest tab and "take care of it", sometimes it's just a news story I want to read, sometimes it's something I kept opened because of the information on that page.
If I don't do that I will have a thousand tabs opened and will never actually do anything about it.
I use it more as a glorified low priority to do list. For example some page I was reading (from HN) linked to a recommended article "How to Build Stable Systems" (https://medium.com/@jlouis666/how-to-build-stable-systems-6f...). I ctrl-clicked the link to open it in a new tab, because I'd like to read the article eventually even though I don't have time at this particular moment. So when I have a little bit of time I'll work through reading/dealing with my open tabs.
Open all the blue links on a Wikipedia article in tabs. When you are done, move to the next tab and repeat. After a while, you will have hundreds of tabs. Read them all and you will gain general knowledge on a subject that will be much better than if you were to read only the first article.
That's only Wikipedia. I do the same things with forums, documentation, stackoverflow, etc.
