NTR actually is very much a normal tag. Also with clear definitions: netorare and netori. It doesn't take 5 minutes to google it. I'm not struggling through it again now. I've done that enough times.
The real Problem is that a lot of players don't understand the real NTR meaning or don´t want it to be true. They prefer to use their own, fictitious definition, which defines any sexual activity that does not affect the male MC as NTR or/or doesn't even really differ between cheating and NTR. This way it is absolutely wrong, I've already read a lot of nonsense here in the forum. But it is absolutely impossible to tell people about their mistake. If you try that, you get facepalms, stupid sayings or insults. But a factual discussion about it is not possible most times.
Accordingly, more and more developers keep out of the discussion. Therefore we have to live with the fact that the NTR tag in this forum is almost always wrong. It is simply not possible for a developer to truthfully work with a tag that a large number of players simply do not want to understand, and who hold on to their wrong definition, despite all the explanations.