The problem is that NTR readers aren’t one monolithic group.
A decent chunk of NTR readers play the game for the good ending, but fap to the NTR scenes. Why? Because NTR scenes are hot but they also want the main characters to do well and be happy. Contrast is the spice of life, and "what could have been" scenarios are a secret guilty pleasure of many.
As for intentionally making a stupid choice to get the heroine NTRed, this also happens a lot in linear NTR games too. Except you don’t have any say in avoiding the stupid choice, the idiot cuck makes it automatically in your stead.
Personally, I find the second scenario more aggravating, because this lets the dev make up as many bullshit scenarios as they want. Whereas in non-linear games, the dev has to account for player agency and actually write unique consequences for each choice.
As it stands, both linear and non-linear NTR games are great. It’s not like one form is superior over the other.
That being said, non-linear games are much harder to "get right" because you need to account for all the different choices out there while making sure they don’t seem too out-of-character. Since you are making at minimum "two routes," your attention is essentially halved for the NTR route. Which is why so many "avoidable NTR" games seem so damn unpolished. Because they are, lol.
In the end, many "avoidable NTR games" are really just NTR games with token vanilla scenes thrown in. I've only played very few where there are actually H-scenes in the vanilla route.