I mean, it's highly unintuitive, which I would say makes it difficult to understand. The main weirdness is that lowering the rent would force a revaluation whereas letting the building sit vacant for an extended period of time apparently would not. If this is truly driven by regulatory capital requirements, then it seems like a gap in the regulations.

Also foreclosure generally isn't the only option: the borrower could, for example, agree to repay part of the loan early, or give extra collateral, both of which would increase the LTV (and this would be better for the bank).

I'm not saying the explanation is wrong, but I don't blame people for finding it difficult to understand. Other factors contributing to this are probably borrower relationships/negotiating strength and the high costs associated with foreclosing.