Sure, but I'd like to be able to filter by all as well on occasion to see what the rest of the community is talking about in much the same way that on reddit I sometimes only look at my subscribed subreddits but sometimes use r/popular.
And as you say it won't help with comments and from what I can tell after even a short time here, it isn't uncommon to see lemmygrad users in comments on lemmy.ml so even if I were to only use local/subscribed I would still see content that I don't want to see by staying here. That could potentially be a temporary solution but clearly means that lemmy.ml is not the right instance for me. I think I might rather just leave Lemmy altogether until there is more adoption and therefore somewhere that suits me better.