People not being able to be evicted from their homes arbitrarily is a bad thing?

There's a counterparty to that transaction, and presumably has some reason to want to cancel it, so they're being harmed in some way. Even if you don't have sympathy for landlords though, there's still the second order effects where all landlords discriminate against tenants more, because they know that getting rid of bad tenants is going to be a pain. It's similar to the employment situation in Europe. Making workers harder to fire might sound like a great idea, but it also makes employers more reluctant to hire, especially if they can't easily get rid of them afterwards.