I think that if a nommer is abusing the system by picking exclusively from their friends or family, writers will soon realise that they are not getting a fair look in, and ditch that pub. It shouldn't be necessary to have a limit.

Shouldn't. But probably a max of 5 per month per writer per pub would be reasonable.

It does happen that you can get a shit-hot, prolific writer who produces a whole bunch of nommable stories in a month, especially if they form a series (e.g. episodes of memoir or ongoing travelogue).

I've had that from 2 different authors in recent months, but a cap of 5 would have allowed all their valid and valuable work to be nommed within any given month.