FWIW, the Biden administration is doing a decent amount of behind the scenes work on housing costs, both directly (funding low income housing) and indirectly (incentivising cities to change laws that decrease supply and prop up the local landlords). Some of the reasons (IMO) he doesn't talk much about this are:

1. Small-scale landlords are a decent chunk of the Democrats' donor base. So although this isn't going to significantly negatively affect small-scale landlords (not that I'd care if it did - it just isn't), too much messaging on that front could have a negative effect on donations.
2. Some of the least reliable voters that the Democrats are depending on this year are sufficiently leftist to dislike any attempt that isn't fully public housing. And none of what the Biden administration is doing will result in massive swathes of public housing. Some places might get some at the margins, but mostly what's happening is that local governments are working with non-profits to provide more affordable housing, using the influx of federal cash to make it happen. Messaging here needs to be very careful not to give these folks an excuse not to vote.
3. Many of the voters who are (somehow...) on the fence between Biden and Trump are also very NIMBY. So if someone from the Biden administration were to come to their town and say "Joe did this!" that could actually dissuade some undecided voters.

Is it stupid? Absolutely!

Is Biden doing enough on housing? Definitely not!

But a big chunk of what he is doing is flying under the radar, partially because they're not advertising it and partially because it takes longer than just one presidential term for these kinds of projects to make it to fruition. The first development in my city that took advantage of Biden administration policies finally broke ground in September. The first actual affordable unit to come out of it will be available in 2025.

Trump lies constantly but he's also very blunt and realistic about problems (as long as he can disclaim responsibility for their cause). Do you think Trump will avoid talking about this as it gets closer to election time? No, he's going to be blunt and realistic and pragmatic sounding and Biden will come off as out of touch to the incredibly large base of quiet regular lower middle class and middle class people affected by this. Probably 40% of the vote will be won based on how people are feeling about this and Biden is responding to that by saying "Actually, you're feelings about the economy are invalid because according to my policy wonks, the economic data is good." It's insulting and enraging to the people who are struggling. Many lower middle class and middle class people don't care that much about abortion or trans issues or whether Trump is a pathological liar being paid by a foreign country to destabilize America. They just want to be able to pay their bills and not be so damned stressed out. Biden absolutely does not get it. This is also the fault of the officials surrounding Biden who should be doing a better job of addressing these problems. Biden is very old and generously ran against Trump out of kindness because he knew he'd be more likely to win. The people around him should be addressing this, the DC insiders and people he took with him into office, and no one addresses the problem or crafts policy. This is an easy win for Trump and he knows it, Trump is not stupid contrary to what many want to imply, he's enormously intelligent and just mean at times and cruel towards many minorities, but Trump needs to do barely anything to win at this point. You don't get into Wharton as an idiot, even if you come from money, so liberals who want to claim he's stupid are doing themselves a disservice by underestimating Trump. Trump is greedy and corrupt and cruel and incredibly intelligent, and if you don't get the fourth part you miss the threat. Trump also at times has good intentions and people sense that, which is also a threat because he doesn't seem completely disingenuous. Biden's campaign is like the Titanic in a field of icebergs and all Trump has to do is just wait. For Biden to win, he'd have to make a lot of changes which he should have done over a year ago, and based on the team around him that hasn't dealt with the problems correctly, he's probably not going to make the right choices on this. If he makes superficial meaningless gestures on this issues in a last minute hail mary pass, it's not going to matter. Voters aren't stupid. I wish I could write Biden or his team and tell them what they should do, but I'm some nobody. No one would care.