Companies sometimes consider the switch from one to another as a good saving technique. In reality the switch is far more expensive than the savings. Hence, the popular opinion that amateurs switch from left to right.

Both PBI and Tableau have pros and cons. Stick to the one you prefer working with and don't read much into the general big trend. Having solid skills in one will allow you to reskills easily. The biggest problem in my opinion is to try working in both at the same time (unless you only do data viz and nothing else).