Get rid of accounts that have been inactive for a year to make names available again.

Bmorgan13

Finding a name that isn't taken is hard these days, let's get rid of some old accounts that don't deserve their names to make it eligible for others.

SummonerNR

Finding a name that isn't taken is hard these days, let's get rid of some old accounts that don't deserve their names to make it eligible for others.

Kabam already does that. Happens after about a year (or maybe between 1-2 years).
You can just do random searches of different alliance tags (like AA, B.B., etc) and see old alliances. Their members will still be there, but their summoner names will have been cleared out to just show dashes.

They should probably do that with the alliance TAGS/Names as well though, to make it easier for new Alliances.