I don’t think it’s assumed at all. People just come into these conversations with overly-simplistic solutions (Just Add Housing™) and if anyone disagrees or points out that it’s actually a complicated, multi-faceted problem, they’re wrong and a NIMBY. Who pays for it all is a huge issue, and I don’t think there is an obvious universally agreeable answer. If there was it wouldn’t be fought over so fiercely.

But don’t point that out here! It’s not enough to agree that the area needs more housing—you aparently have to also profess that it’s obviously the only solution, and that there are no trade offs or complexity to consider.