That said, there are a lot of things tagged as yuri that are just subtext on this reader anyway.
I've noticed, and it's pretty frustrating at times. It dilutes the tag down to meaninglessness, and makes it un-useful for finding the type of story you are looking for.
Two girls having sex? Yuri. Two girls making out? Yuri. Two girls in love? Yuri. Two girls that are friends with each other? Yuri. Two girls in the same comic panel? Yuri.
Everything else is broken down and minutely characterized. Is there Pseudo-heterosexual subtext between a female wolf spirit and an sentient shade of blue that identifies as male on page 23? There's a tag for that. But if you have two girls sitting next to each other on the train, that's just yuri. Argh.
Of course, even if there was a great willingness to go through everything and correctly label things, there would have to be some sort of agreement on what "yuri" is or isn't, and if "shoujo-ai" is the same thing or different, and who gets to make the judgement call on edge cases.