The AHF provides a place for 16U "B" teams to play. There is no such thing as 16U-B in most leagues. So if you were a 15 yo heavy team, you previously had a few bad options. Get smashed in 16UA or play in 18U B or rec division against much older players. Neither of those options are palatable.
Out of the bottom 50 teams in the country according to My Hockey Rankings)...11 of them are in the AHF 16U LA. Most of the games are between teams within 2 or 3 goals of each other on MHR.
This keeps the competition fairly even.