Many of these albums are not put up by the label and registered properly for streaming revenues to the collected, so are piracy in another form. They often get taken down again fairly quickly.
Where the label has done it, it seems confusing to do that but then release it on CD too. They are literally killing off their own sales.
It's one thing to licence it to a full streaming service such as Spotify, GooglePlay etc but just to put the whole album on YouTube is daft I think.
I used to run a legal music streaming/download service and labels/artists are often so keen to get the music out they have no view on the commercial aspects, especially in this area of transition to fully digital.