You don't need to subscribe. You are in CC when people want you to be notified, otherwise there are web interfaces you can browse. See https://lists.gnu.org/archive/html/guix-devel/ for example. On each message there is a button: "reply via email to [...]".
I usually know, when the interface is not too shiny, that the content might be good. It's the same with HN. And those interfaces are still very easy to understand and use.
That being said, there is certainly room for improvement.
There's something to this idea, I think. The less polished a tool is, the more I'm inclined to think it was built by the community for community use. There's so much talk about enshitification, and I'm struggling to recall when a tool with a less-than-polished interface had that problem.
The example that springs to mind is spamgourmet, which has a FAQ about why they don't redesign their site. I've used the service for about 20 years, and while there is a bit of a gatekeeping vibe to it, there is also a good reason: they have very few resources for support, and want to attract a certain crowd to minimize the support burden. It seems it's been working for a couple of decades, at least.
> Q. Couldn't you make the whole thing a lot easier to understand by redesigning your site and providing instructions in a more clear way?
> A. Probably. Frankly, we're trying to build a user base of people like you, who probably have some familiarity with the way email works and who are willing to read FAQ's. This is to keep our support burden to a minimum (this is a non-commercial service). So far, the approach has worked well -- just about all our users hit the ground running with no need for support, and it's our belief that those users who would require support generally don't sign up in the first place, perhaps because of the geeky presentation of the site. That's not to say we don't provide support where it's needed -- after skimming this FAQ, please don't hesitate to write if you have a question or believe there's a bug.
I tend to actively seek out projects like this, since I don't mind the blow to usability, and very much appreciate that they provide the service and don't pepper me with annoucements about their new improvements or their changes to their pricing structure.