Oh. OK, now it makes sense. I was wondering how IRC would help me with tabs.
OK, that was a misunderstanding. I found out about this gesture eventually. But it's of no use: You would have to type the URL in manually, and even if you would be willing to do so, there's no way in Fennec you could actually see the URL of a link.

Like when I'm on ITT's front page: In MicroB, I tap&hold on a thread title, choose "open in new window", do so with all threads I want to read, then close the first window and read thread by thread, each in its own window. I can't do this with Fennec: I can open a new, empty tab, yes, but what for? There's no way I make the thread open in this new tab. No tap&hold, no "open in new tab" and no "copy link location" so that I could paste it, not even a way to view and re-type the link URL.

And that's just one use case where Fennec fails. I would have hoped they'd fix these alpha-issues in the beta release.