Some person somehow gets to be the leader and bosses people around. Those people aren't always the brightest or the most compassionate. They often are pushy, they are somewhat totalitarian, they really don't like their ways to be questioned. Sometimes (not always) they are the most dedicated but only because they made volunteering their identity or their main source of self-esteem (this can either happen because they don't have anything else going on in their life OR because what goes on in their life do not satisfy them).
They are often "open to new people, ideas and contribution" only as long as anything new is very well aligned with their (personal) line of thinking and/or does not question their "authority" in any way.
Either way, I've seen that happen too many times to take volunteering any seriously.
In my case, local community orgs are usually run by older, often retired people. Doesn't mean there's no drama, but it's not the same kind of drama you'll find in predominantly younger organizations.
I stay volunteering for the people I work with even more than my investment in the goals of the organization.
You can find something like that - keep looking.
A few years ago I joined my rural neighborhood council, and I’d never been around so many people consistently being generous with their time and energy. It’s really uplifting, and you end up learning a lot from each other in the process too.