I think a massive difference between Twitter and Reddit is that Reddit isn’t very user-centric. It’s not about building a “personal brand” or amassing individual followings.
That’s why I believe a decentralized Reddit clone (akin to Lemmy) has a much larger chance of thriving.
I believe it’s more confusing to less technically inclined people though, since @ is used when adressing a server in a community as well.
So I’m afraid it’s something that will hinder adoption. The advantage of the ~ strategy is that it feels more like something like email, as well as having the whole unix homage.