I don't think the problem is a lack research. I think the problem is that terms describing art are often subjective and few things are built without having inspiration.
People who write games play games and get inspired by other games they've liked. So while someone might declare something being a first in a genre, someone else might say "this earlier game is similar enough to that genre that it still counts".
It also doesn't help that 3D is such a (mis|over)used term that it can apply to a broad range of different styles that are worlds apart from one another (as I describe in more detail here: https://news.ycombinator.com/item?id=23668287)
