Maybe try explaining why you don’t use Facebook, and why it is not an appropriate, inclusive way to organize the group. Or, maybe Facebook has some kind of E-mail gateway that can notify people who are not on it (I have no idea, I’m not on Facebook either). You’re just one person, but if the group sees more people not participating because of their bizarre insistence on use of social media, maybe they can eventually be convinced to change.
This seems so weird to me. I help organize some local groups centered around hobbies and games, and none of them use Facebook because we know not everyone will be there, and we don’t want to exclude people. Sorry, but that musician group seems pretty poorly run.
To those people you are the weirdo refusing to use the convenient platform that everyone else is on. This stuff just does not enter their brains because it has become utterly normalised. To them it's not bizarre to insist on using social media, it's bizarre to insist on not using it.
Again: been there, done that. Good for you (and others, even if they don't know) that it worked, but in my case it didn't. Part of the reason is that FB is also the place where events get promoted. The integration is so tight that any other solution is an inconvenience to the normies, ie. the 99%. You have your events, your communication tools and your audience, all in one place, it's effective. FB is eating the world really... convenience for the masses.
Luckily, I have other hobbies that are less prone to this, mostly because they don't involve much event promotion if any at all and don't need any audience to exist. Example: my local shooting range uses a mailing list for communication and you can always hang with fellows at the club-house.
I'm a meetup organizer and sometimes get this but the other way. People insist that our current platform is not appropriate or inclusive because it requires an email signup, or the group chat is on a Meta-owned platform, or whatever. Who are you to say that your opinion on what's inclusive or not is correct? Choose something other than Facebook and you'll get others saying you're not inclusive because you're not there.
No one has "bizarre insistence" on use of social media, they're just there and it's the easiest option for all parties. People like you and me are the ones who are perceived as the ones bizarrely insistent on not being on social media. This doesn't make it wrong, and it's luckily slowly becoming more and more accepted, but it is important to keep in mind.
You are right that ideally groups like these should cater to all audiences but that's a lot of effort, and many organizers do it on a voluntary basis, not as a job. In my case, I know that 98% of people are included in the media that I use for my audience, and catering to the last 2% would double my workload. Not happening.
Since as far as I know, an E-mail address is required in order to sign up for Facebook and other social media, E-mail users must be a strict superset of Facebook users. It is clearly more inclusive of people.
As far as workload goes, we have not found anything lighter weight and less maintenance than an E-mail list.
This seems so weird to me. I help organize some local groups centered around hobbies and games, and none of them use Facebook because we know not everyone will be there, and we don’t want to exclude people. Sorry, but that musician group seems pretty poorly run.