Often people this days have ideas to take anything with them, when leaving home.
Likewise when leaving back... 
That wouldn't work. Nothing, aside of robes and bowl (...the eith things), are proper to take into new relation. Not even phones, books, not to speak of
old relations 
.
Once taking on Nissaya (foundation, teacher), one lives on relaying on him. Even such as reading other teaches books, or engage online with others, receiving, giving, if not given leave, would terrible disturb the new relation and under circumstances, actually break the Nissaya. In cases when relation to "unfriendly" people toward the teacher are maintained, it's actually a fault in regard of the duties of a disciple toward his teacher.
It's similar like if wishing to bead another one's egg, an inhonest relation, a "thinking like a thief" if going impure into a relation, or while staying there.
Of course one is merely free to chose and to change but there is a strict "monogamy" on the disciples side required.
While the Vinaya and commentary mention "hearing even voice" of another (former) teacher can break Nissaya, there is less reason why other medias wouldn't function in such manner, on mental level as well.
It's certain the case that today many actually mentally, at least, yet not formal, have taken on relations with teacher, and many teacher, maybe without being aware, actually carry a lot of "silent" disciples around.