I wasn't aware that the restriction broke anything.
I don't like that the solution to this is just to remove the restriction because that's essentially replacing one problem with another. But anyone who knows a lot about housing knows that SE don't exactly rank it high up on their list of things to improve. So I'm not surprised if that is what happened.
And before anyone says the restriction needed to be removed for the fc leader mechanic would work; SE could just change how that mechanic works.
For example the leadership could get automatically passed on to someone without leadership of a fc house on that server. In the event that no one in the fc is eligible due to every member being a fc leader on that server on another character, then the first player could get notified that if they relinquish leadership elsewhere they will become eligible to take on the leader role in that fc. They have, let's say, a two week window to redeem the fc and if they do not, then the next player gets the same option and so on.
SE could have both systems work fine. But well...they need to care enough about the housing system to do that. And they do not.