Direct to the Bank vs Broker lending

[Carl Snyder]

Ladies and Gentlemen of the Bigger Pockets Community, thank you for taking the time to entertain my elementary question.  I'm still in the "information gathering" stage of my RE investing and in all I've read and listened to, I've yet to see or hear any evidence that would explain what the differences between what broker lenders can offer vs. going right to the banks.  My understanding is that most lenders have a 4 property minimum they'll assess to investors making it difficult grow.  Why would I not just opt to work with a mortgage broker that represents say 12 different lenders and never have to make 50 phone calls to secure financing?