The claim isn’t “there aren’t large drug problems I. California/Oregon” which is what you are correctly stating is true, the claim is “drug problems are not the primary driver of homelessness, housing costs are”.
Saying “California and Oregon have effectively legalized drugs so that’s why there is homelessness” just isn’t an accurate statement. As noted in other parts of the thread, people who use drugs will happily rent a place of it is cheap.
Now is it a contributing factor? Probably a minor one, yes. But the primary driver of the size of the homeless population is housing costs, and for the unsheltered population it’s definitely weather. New York actually has a very sizeable homeless population, the difference with California is that people are much more likely to be living in shelters there.