What makes them “feel like 1970s technology” to you, and—more importantly—why do you say that like it’s a bad thing?
Most of the opposition I’ve seen to using mailing lists for technical discussion has basically come down to “young people think email is old and gross” and my position is that people reacting that way have some self-reflection to do and to get over themselves.
What makes them feel like 1970s technology: everyone has to manually manage their own archive and pay storage costs for media files, there is no way to share history (if you want), there is no integrated search, differences in clients mean that people have different experiences of the same message, there are no affordances like reactions that allow people to easily interact with a message without sending an entire separate message.
But maybe I should have said late 80s, early 90s tech. In the 70s, if you were communicating with others on a computer, you were almost certainly using the exact same software on the exact same time-shared system, where at least there was a symmetry of experiences (but no multimedia). The explosion of email clients happened in the 90s, mostly.
Oh no, people have to consider how they engage with others’ writing! They can’t just push a “like” or “thumbs down” button! There will be social pressure against it if they try to just send around picture or video memes instead of writing something thoughtful! And worst, everyone gets to be in control of their “experience of the same message,” by using the mail client that works best for them!
All of the reasons you say mailing lists are, let’s say, “dated” are actually benefits of using them, especially when using them for engineering purposes.
I agree that the available features can steer the online community culture and behaviors, but it's not determinative. I don't see why online communities should give up useful features just because other communities use them in a way you don't like.
I've been using mailing lists for about 30 years now. In the days before social networks, there was tons of forwarded crap and email chains, such that debunking them was a cottage industry. This behavior eventually moved to Facebook and Twitter which is perhaps why email lists seem more civilized these days, but I don't believe its the features that are driving it.
Most of the opposition I’ve seen to using mailing lists for technical discussion has basically come down to “young people think email is old and gross” and my position is that people reacting that way have some self-reflection to do and to get over themselves.