It might be better to instead say, what does a discord server offer to you that a mailing list does not for your technical user group? I think most people are on discord because its fashionable and they are unfamiliar with older technology like mailing lists, which were more common place when they were only children perhaps.
> what does a discord server offer to you that a mailing list does not for your technical user group
Having to click on multiple links to just make sense of a conversation?
It's the reason I can't even get myself to follow places like NANOG and LKML; because the experience is just so painful. It makes you almost immediately want to disengage from the subject matter.
I'm almost never looking for a mailing list. I've been on the internet for 20 years and they never fill the same niche as IRC. Same for discord. mailing lists can't do what it does.
I've never successfully used discord, sure I have an older computer and slow internet but I just don't understand why facebook and the like are fine but discord never displays for me.
I would love mailing lists to be a thing again, but the experience of using email is just so bad for me. The sheer amount of unsubscribing I have to do to make it usable - not even taking spam into account - makes email a place I don't want to spend any time.