Mead Hall in Minneapolis does a 10 week league. Each league night is 3 rounds of Swiss with the standard prestige system. The winner gets 1 alt prize card and a second prize card is given away in a random drawing. The league is scored as follows:
5 points for showing up to a league night
3 points for missing a league night
1 point for winning a game
1 point for bringing one ID you haven’t played yet in the league (max 1 point per week)
After 9 weeks, there’s a cut to top 8, and week 10 is a double elimination tournament. It works pretty well for encouraging people to bring new IDs, although part of that may be due to the fact that the Minnesota meta is full of self-admitted Netrunner hipsters who refuse to play standard decks most of the time (I’m one of the few exceptions). The last league was won by a 54-card Chronos Protocol deck that beat my Prepaid Kate on stream (Batty psi game trashing Atman 6 before Archer encounter, oof) paired with Siphon / Vamp / Opus CT piloted by the player who won our Regional with nonstandard EtF and Whizzard decks. In that league I played Mushin Cybernetics twice, Biotech rush, ITD EtF, and some other weird stuff in addition to my usual mix of good standard decks, and I played against everything from Mushin Medtech to London Library double Femme (lost that game with ITD EtF!). I made the top 8 despite winning 0 games with Cybernetics or Biotech, because the point for bringing a new ID each week kept me in the running.
IMO, rather than banning IDs or cards, it’s better to provide positive incentives to play with nonstandard stuff. We’ve found that people really want the league point for a new ID most of the time, so probably 75%+ of the league brings at least one new deck each week. You could increase the “new ID / new card” incentive to push that further, or add league achievements for doing nonstandard things, e.g. “win a league game as NBN without AstroScript in your deck list” for 2 league points. You’d need a long list, but I think it could be done, and I know at least some metas have tried stuff like that out with some success.