Rent, as well as the homelessness that comes along with not being able to afford it, is what forces many of us into selling our labor and makes us much more desperate in doing so. Housing as a basic right would be the single greatest victory for the labor rights movement. It's difficult to express how much power that would put back into the hands of the workers.
So of course, guaranteed access to housing is the real goal, but I have my doubts that we can make this happen in one move (as nice as it would be). Much like our fight to take back our places of work, we need to take steps in organization toward realizing the true ends.
Tenant unions and labor unions have a lot in common. Vulnerable people who are beholden to capitalists have more power when they negotiate together. That's harm reduction right now, but more than that, it's practicing working collectively. It's getting in the habit of treating these things like they belong to us and not to them.
Clearly, tenant unions are behind labor unions in every way, but that doesn't mean we should give up. People had to fight to get legal protection for labor unions (and we're still fighting to get those laws enforced), and we are going to have to fight to get those protections for tenant unions. It won't be easy.
But we aren't without advantages. Evicting one tenant is difficult, long, and expensive. Evicting even half of a single complex would be impossible. It would not take many people going on a rent strike to severely impact the cash flow of a company mostly/exclusively invested in real estate.
The reality is we always had the power all along. We just have to come together and use it.