Maybe you need to find different communities. Being part of something isn't a need, it's a want, and you either accept that you want to be there and take the good with the bad, or you accept that you don't like the bad and give up on the good.

Ask any psychologist wether being part of something is a need.

Being part of something is a need, but being part of a specific community is a want.

I'll grant that as a theoretical rule, but most communities are not tech communities. Suppose that you're able to pick one which is not dependent on any undesired proprietary/attention-sucking/etc. medium but is still interested in the things you're looking for. (Many communities are not very fungible.) One day:

“Hey, I like what we're doing, we should set up a group for it to make it easier to keep up with events and stuff.”

“Telegram? That's what everyone else seems to use.” “Yeah, I've already got that on my phone.” “Me too.” “Yup! And I've got this great sticker pack I want to show you…” “Hey, can you show me how to install it?” “Sure, it's easy, just…”

“Awesome, I'll set it up.” (tap, tap, tap)

(Substitute Facebook, or Discord, or whatever else.)

Gradually people just kinda forget to post things anywhere else, because it's convenient and lets them post from their phone and they get all the encouraging responses they wanted there, and so it gradually becomes common knowledge that that's the place. The choice of platform isn't in their community identity, so the default is whatever people gravitate to that doesn't require doing something unusual.

If you don't integrate psychologically with the popular platforms, you're not really choosing to not be part of a specific community, because that's what “popular” means: you're choosing that the set of communities you can explore in the first place is whittled way down, and your membership in any you do find is now precarious. “Pick a community that doesn't do that” not only raises the difficulty at the beginning, but it also doesn't save you later.

I was also kind of thinking about _FOMO_, but just in terms of messaging apps. For instance, if I were supposed to be getting a ride with someone and my notifications were off, wouldn't I have to be checking my phone more since i'm now manually checking for messages about the lift, instead of being pushed them as they come in.

It seems to me that message notifications, at least, do keep me from checking my phone.

Are these some sorts of business communities where you're actually working for a tangible reward to further your career? Even if they are, this sounds really crazy and wrapped around an axle to me, if this is your steady state level of interaction, especially if this is multiple communities you're talking about. If you're bootstrapping yourself as part of a marketing or sales push, you can dedicate a time slot to working it, or consider this level of intensity as a short-term effort until you've established a more self-perpetuating network.

If that's not the case, are you really sure that you need to be doing any of that? Especially "get a word in on something important" is awfully similar to https://www.xkcd.com/386/ .

Ignoring the “business” part of your comment, because that's far from the only reason to want to have broad social ties:

Dedicating a time slot in the usual sense is very socially costly if they've gravitated to a presenceless, fast-moving platform, because psychological consensus and topic closure operates more on the perceived speed of communication of the group. If 90% of the other people respond within an hour, and you get there eight hours later, the conversation's moved on, so if everyone else is in the habit of checking their phone every fifteen minutes, there's pressure for you to be too. So, yes, you can “dedicate a time slot” at the end of every pomodoro, if that's what you meant.

This is more true in “channel”-based environments where “new in thread” is inconvenient or unavailable. If you're not careful, you can even be disruptive. Even on slow-moving, old-style Web forums, “necroposting” is considered rude; a chat-like medium with little to no threading support can just lower the threshold for it from weeks to hours if there's enough activity.

For the other part, I'll grant that “get a word in on something important” was badly worded, though I can't think of a better phrase this instant. I was imagining things like “we've changed the meetup location because someone raised a problem, is this okay with everyone or does someone need a ride” or “I'd like comments on which direction I should go with the next part of this piece” or “I'm going to see if some of us can do X together tomorrow, I want three more people, who's with me”. All of these can easily render your participation irrelevant if you show up too late, and “too late” is by default defined by what's usual and convenient, not by abstract considerations of what's good for people's habit formation.

This assumes that only things worth any value in life are those with "tangible reward to further your career". I dont really agree.

No, I'm simply saying that if they're killing themselves by maintaining such a high-stress & rigorous involvement, they should at least be getting something out of it and should ensure that that extreme level is short term, because it's not healthy.

If they're doing it only because they kind of fell into it as baseline socialization shifted, they need to step back and reconsider things because it's not healthy.