I agree with Kurtis in that most solid leagues out there are invite only. There are several leagues that are “first come, first served” and they often are coincidentally the ones advertising for owners every other week.
Some day the USBA might have an opening (hey, work with me here, it could happen
) and the person that takes over that team will not necessarily be the first person that sends me email. It will be someone who has expressed some interest already and seems like a person who would make a great addition. I will "invite" the person I see as the best fit for the league.
As Sean put it, a guy takes the time to start up the league, there is no reason why he should not be able to pick and choose who's in it, even if it is the "same old" owners that Commissioner is familiar with. I’m not saying it’s the best way, and not the only way, but I do not begrudge it.
Of course there is a possible downside if you are not open to adding "fresh" people to your league. When the USBA expanded by four teams, I added two GMs I was very familiar with and two who I have never shared a league with. After doing some cursory reference checks, the relatively "unknown" guys seemed like good fits and have worked out extremely well! Playing with new people is often refreshing and invigorating for a league.