I suppose an annoyingly trendy answer would be...
Pros: I am confronted by people with violently different values and opinions to my own.
Cons: I am confronted by people with violently different values and opinions to my own.
I'm not trendy.
So instead...
For me the hifi community starts on-line. I don't know anyone ok who is a real hifi-nut who I have not met online.
For me these communities have the following functions and pros:
1. Practical. Forums have provided me with information about, and access to hifi kit that I would have been very much less likely to have discovered if the online hifi community did not exist. So for me, a vital source of information.
2. Social. There are some senses of connection and identity that I get from the hifi community. Also, several people I have met online have become friends.
I find the cons of the hifi community are those that "plague" almost all human social life. Namely politicisation, tribalisation and status-seeking. (And, I feel myself getting sucked in to that too of course.) Some of the more extreme stuff that I see going-on in the wider hifi-community makes the polarisation in the UK over Brexit seem like helpful and rational debate. I suppose one 'pro' of the partisanship that segregates the hifi community is that it is as entertaining as it is depressing.