It makes sense to me. The number of people who actually create useful open source software is so vanishingly small compared to the number of people who use OSS,

It makes sense to me. The number of people who actually create useful open source software is so vanishingly small compared to the number of people who use OSS, it seems obvious that we should optimize for their time, not the other way around. I agree with you that using mailing lists or GitHub issues or whatnot would be globally more efficient, but if I’m working on a product, I’m going to work in the way that is most efficient for my time. I owe my “customers” nothing because they are not paying for my work. We keep seeing discord as a means to communicate about products because devs see it as the best use of their time. The fact that so many people use it should be an indictment on the alternatives, not the devs who choose to use discord.