But - originally - you give a number (be it real or Mozilla or "burner") in order to be contacted by someone (and then somehow it was leaked to the robocallers).
The moment you change or abandon the number (be it Mozilla or "burner") that someone won't be able to contact you anymore.
But if you keep it, with the burner at least that someone will still be able to call you at the end of the month (when the the robocallers will have already eaten the 50 minutes allowed by Mozilla).
It would kind of make sense if you could "open" the relay when you need to 2fa, and then you close it again after. With this usepattern you would only need one alias, that would be closed 99.9% of the time.
But if you can use a unique number per service, you now know which company is selling your PII and you could address that either by switching to a competitor or, depending on the legal specifics, sue/expose them.
That's a shame, it wasn't entirely clear from the article but I assumed it must be multiple numbers since it didn't seem to me like it would be all that useful otherwise.
The moment you change or abandon the number (be it Mozilla or "burner") that someone won't be able to contact you anymore.
But if you keep it, with the burner at least that someone will still be able to call you at the end of the month (when the the robocallers will have already eaten the 50 minutes allowed by Mozilla).