Mate that's just your preference, everything can be mixed, even stuff like harem and NTR can be mixed in the proper setting such as games that are about protecting your harem from whatever, but then people based on preferences will mix their interpretation and say that "if a game has NTR tag it can't have the harem tag!", but in the end said game could end up being in a perfect harem situation or a perfect NTR situation.
If the point of the critic is that just because a game has a mother or sister shouldn't mean to get the incest tag I can agree, it's necessary that said characters have some sexual attraction/lust for each other. But other than that I can only recommend you to blacklist NTR and seach for incest games since that will probably give you the optimal games to your liking.
Trying to take out tags from games for a subjective reason is pointless and will make life harder for people to find what they want, for example I'm the freaking weirdo that searches games that have both harem and NTR, since I want to win in a game but have some risks and consequences. If that harem purist sect that demands to take the harem tag out of any game that has the NTR tag was heard I would have a lot more difficulty trying to find what i want, same will happen with those that seek NTR+incest.
