Solved

doubt

What are the advantages of climbing first to a pro or elite league?

Get more reputation because you will race with high level managers

I went up to recruit for pro, and I noticed that the managers of the recruit developed more and gained more xp points because their league was full, while the empty pro did not yield adequate development.

An empty tier isn't very beneficial, nor is an inactive one.

If you are promoted to Pro or Elite, you definitely want it to be filled so you don't feel lonely or bored.