Squad hopping is a problem when:
1 guy creates a squad, jumps in a jeep, hauls arse to the main base. Jumps out , and 5 people spawn on him, then one makes his own squad and the last 2 people spawn on him. almost instantly the whole 8 person team is at the base WITHOUT having to fight for it. That is an exploit. Period. Whi not load up an APC or 2 with the squad and roll in as a team?
As for the single guy in a base asking for backup, Quit trying to be freaking Rambo. Roll into the base WITH your squad. Then the backup is already there! what a concept. My group plays together all the time and we play as a REAL squad. We usually clear out servers when we roll in there. The game is about sticking together with your squad, working as a team, and shooting skill, Not the ability to suicide and join a squad with better location.