Raid is moving towards standardising bp/w longhose.. Currently I don't know any instructors that don't teach like that, but it is still allowed
Here's one.
...as to the question. Some people need taught in person with a professional instructor to safely make minor equipment configuration changes. Some people enjoy that learning method even if they could learn another way. For most of us, I think we learn as we go from a variety of sources. A dive buddy, the internet, a book etc.
To each their own.
Cameron