Firefox has a perfectly good bookmark system.
Some people mention "read it later" features, which I personally use. Safari has read lists, but I would argue these are also poorly understood and under utilized by most people.
For me, I believe a solution is something like "read it later", but lighter weight, easier to manage, and more integrated so that it doesn't just end up being another out of sight, forgotten backlog of things you wish you had read.
Except in cases where we really do know better and the user is likey just digging themselves deeper (e.g., creating security problems). Then they deserve a warning.
If you were WalMart manager and someone came in and a schoolteacher bought your entire inventory of crayons and wanted more, would you not order more for them? Or would you say "you need to change those kids' habits so they aren't breaking all those crayons".
Thousands of tabs may be a fringe use case, but clearly, you can approach the 32-bit address space limit under much more sensible loads.
Pocket, Instapaper, etc. are nice enough for reading things later, but they don't handle the use case of bookmarks as a reference system. I'm not aware of anything which does that well.
"You're holding it wrong."
Decisions like these make software that's unusable for some people. It's the Apple Syndrome: You either obey the One Steve Jobs Way or you go elsewhere. Let's leave the Apple Syndrome to Apple, and make software everyone can use.
Halfway joking here but I think perfectly ordinary people who just use a few tabs at a time tends to just use whatever thay get their hands on, -IE on Windows or Safari on Mac.
This means there is already a bias here: Those who use FF use it anyway because there is no alternative that has Scrapbook extension (offline browsing w/searchability), tree tabs (for automatic mind mapping) that also handles 100-200 tabs in a good way. (Read up on David Allen on using your memory for real work not to remember addresses and tasks for why some people find this useful.)