People use that method so they can sell the program as not having a "B" team. No one wants to tell people their kid is on the "B" team and that is a problem. It's ok to have "B" teams, and it is also OK to play "B" lacrosse if that is the level you are currently at. Why we need to try to justify a lower level team is beyond me.
USA Hockey has AAA, AA, and A tiers, but that isn't the case in lacrosse, so program directors are doing their best to make this their model. Now a kid can choose program 1 because they gave him a spot on the "A" team over team 2 which gave him a spot on the "B" team, even though they are the same level.
I coach HS and club lacrosse. I played college lacrosse. My son isn't old enough to play organized yet but I check this site because my parents brought it to my attention and I wanted to see the madness for myself.
If my son decides to play lacrosse, I will pay for the team that he makes and deserves to be on. The team that he is comfortable on. The team he is excited to wake up and go to. If he is the best kid in the B bracket I will say that proudly. If he is a third line middie on the A team I will say that proudly (if asked). If he decides he doesn't like lacrosse anymore, I will say that proudly.