Oh yeah, I definitely agree that it's an undesirable housing option, and that it shouldn't be a priority to grow it into the future.
The problem is that in cities that have regulated apartments out of existence it's the only existing place for renters to live, so we should be mindful of things that will squeeze its availability before enough apartments can be built to take up the demand.
> Do people abuse the process? Sure, some do. They get away with it at most once, because...there's a record of it all in housing court and eviction proceedings are pretty much a deathblow with any landlord doing their homework.
The problem is that for large corporate landlords this is a statistical risk that can be priced in and accounted for across hundreds of units.
For small mom-and-pop landlords renting out their basement, it's a roll of the dice on whether any given tenant will completely ruin their life and be impossible to get rid of.
Of course many people will respond to this by saying that the rights of people to have a place to live are more important than the rights of homeowners to have a bit of side income, but if the law makes it too risky to rent out a second suite, nobody will want to do it -- which makes the housing crisis even worse for renters as there will be fewer places available to rent.