I'm sure it has been discussed multiple times across multiple forums about a desire to have alts as tenants in private housing. When housing is account bound and you're unable to bid on a private house on your new main without destroying the alts house prior... that greatly increases your chances of not having a house period. Then you're left with the dilemma of "Do I keep a house I can no longer really use, or do I destroy it and hope for the best?".
I'm not going to sit here and pretend I know the inner working of servers/how this would be done from a tech perspective, but I can't imagine it's an impossible feat to allow oneself to have an alt as a tenant. If it's a concern of RMT (idk, I just know that is the excuse with mailing to alts/adding them as friends), it's not like it can't be done with FCs, so there really is no logical reason I can think of to continue to disregard desires of a large multitude of the community. Even if there was a reason, I think many would appreciate it being discussed in a live letter as to why it isn't possible. Otherwise, we are left scratching our heads and doing the joke of Square being a "small indie company".