Cause these kids love that real dope boy trap music and Jeezy kinda abandoned that early on if you really think about it. They were probably too young to be influenced by Trap Or Die or TM101... after Jeezy's 2nd album he really tried to go hard with different topics, more "mature" production instead of the boomin trap type beats. But Gucci kept that flame lit... and ushered in the next wave of ghetto trap producers - 808 Mafia...and also stuck with the Zaytoven trap sound as well. Gucci kept it super hood and ignorant... Jeezy tried to be above a lot of that and make deep songs...and a lot of overproduced stuff probably influenced by Def Jam. Gucci didn't have no Def Jam A&Rs trying to mold his sound.. he just dropped tape after tape of that unadulterated trap shyt... and that's what really resonated with today's 20 year old rappers who were kids during that era.
Gucci made better music. plus, his shyt dont sound outdated like alot of jeezys.