I believe it is because they have no control over the videos that are displayed as options on the page. No matter how good the first video is, each selection on the right produces a list that is worse and worse until the choices are downright unsaintly. There is usually a bad apple after the first list is followed, but never less often than the second or third.
Such is the world in which we live. I suppose the Church feels the benefits outweigh the disadvantages. Any bishop who has dealt with the problem of addiction in interviews probably feels differently, even though it would not be the fault of the Church.
Agency.