There could be lots of reasons for people not publicly posting, as others above have mentioned. But, as with anyone anywhere starting a new job, I hope Dean and Vicky will be welcomed, just like I wish Scott to be welcomed by his R2 colleagues and Chris to be welcomed by his Capital colleagues. The decision was made by the bosses not by the other presenters (I assume).
I'm sure Dean & Vicky fans are thrilled to have them on in the afternoons. It won't make much of a difference to me as I'm looking forward to following what Scott and Chris do next, as much as I'm going to miss having them on together.