I always imagined the only reason to play AL is to meet new people, and if you all get on, over time turn the group into a home game.
No-one plays AL for an extended period, do they? I dont know maybe they do.
I've got people playing D&D AL in my local store who have been playing there for the past three or more years. And for most of that time, we were playing just D&D Encounters (levels 1-3). They were incredibly happy when it branched out into higher-level play, but the point is they kept coming because they enjoyed the games.
The fact is that not everyone can manage a home game. Home games also have disadvantages. Because I've been running games at my store for the past four years, I've met lots and lots of people, some of whom have joined my home game. I've inspired some to start their own games. I've introduced players to D&D, and seen some of them becomes DM themselves. The players get exposed to a greater range of DMing styles than if they just stayed in one home game.
Another advantage is that I get about 26 free adventures each year to run.
Cheers!