I believe that some form of this is pretty common in general simply because that's how people cope with the very fact that homelessness exists in the first place. Like, it's either a massive injustice that pretty much demands that you, personally do something significant about it... or it's "just the way it is", and you can look away. But this latter outlook requires some amount of dehumanization, so people rationalize that the best they can.

The end result is that we’re forced to view the homeless as lesser. We typically throw around words like addict, because we have to. If we admit that there’s homeless people out there who got so based purely on bad luck, that destroys the promise of America.