Let's say BYU offers a local no-star kid early his JR year of high school and he instantly commits. 

The end of his JR season he picks up a few Mountian West offers... now he's a 2-star kid. 

(If the kid really was committed to BYU it would stop here.. as a 2-star recruit)

The summer before his Sr. year he travels to a few west coast camps and gets a few PAC-12 offers... Now he's a 3-star.

If the kid wants that 4th star he needed to be seen by a few SEC schools (who don't recruit out here often... kids have to travel out to them).

Lots of kids don't have the opportunity or money to travel to camps and get stuck at 2-stars.  That's why the local Utah All-Polly camp got started.  However, even they have had recent struggles with changes to NCAA rules.

If you get that 5th star... it means you have some big offers.  What kid is going to pick BYU over a top SEC team?