I hate how that's phrased. No one is ending single-family housing. They're legalizing multi-resident housing.
While that is true, it also ends the zoning that is established to allow people to live in a single-family neighborhood.
I live in a seven-unit apartment building on a block that is otherwise entirely single-family homes. It was built in 1890. As far as I can tell, none of the residents here could be noticed as out of the ordinary by anyone outside of our building; I have my gripes with the neighbors downstairs who play their TV too loud, but it has no effect on the rest of the neighborhood.
I can't say as much, however, for the house next door, which is rented by a group of college students who regularly hold loud parties with dozens of people over. I'm sure they're pretty conspicuous. In an economy where it is already very common for multiple adults to rent rooms in a "single-family" home, it is a mistake to blame people's behavior on the type of building they live in.