Because they don’t want other teams contacting those players after rosters are being posted. It’s pretty common sense to me man.
Welcome to Juniors newbie you really think these invite camps are actually invite camps? Email the team that your interested in playing and you receive an invite to Main Camp. Attend a NAHL combine you will get an invite from just about every NAHL team there is.
At least some of the good USHL teams post rosters so you know who your scouting and what games to go to
Because it’s about making money.