To be fair, the guy you originally quoted was dead wrong... so your statement in this second response is still a little off...
Cuckholding and NTR are completely different things, they serve different purposes, and the only thing they have in common is the fact that the MC's partner is getting dicked...
Cuckholding is more of a "western" thing, its a fetish in which a married man or a boyfriend is perfectly fine with the idea of his LI fucking another dude, even in his presence. Chances are the dude is stroking his tiny PP watching the scene unfold as he "can" (doesnt have to) feel inferior to the "bull" that is breeding his LI... self-humiliation can play a part in this fetish.
NTR is a Japanese fetish in which the most important aspect is that the LI is emotionally hurting the MC, not just by cheating, but by degrading her loved one and mentioning how the new scumbag and the way he dicks her is the most important thing in her life forever more. This one doesnt have to be about stealing a wife/gf only, this one DOES include mothers and sisters... even if the MC isnt romantic or sexual with them... the MC's school bully can come to the house pretending to be the MC's friend when he isnt home, seduce a family member, fuck them STUPID (literally they loose braincells)... and then have them get caught by the MC talking shit about what a waste of space he is, and how they would toss them out on the street if the bully wants, as long as he keeps dicking them...
In this regard the guy who mentioned Netorase, that is more closely related to Cuckholding... in that the MC enjoys that garbage... Netorare means the MC hates the fucking shit out of it... again the "taste" of the player behind the MC is irrelevant, its about how the situations affects the MC... a dude that likes NTR is gonna find both of those scenarios "hot"... just like someone that despises the fetish is going to hate both of them...
Rarely you get the middle ground, like
Thialf or myself... Me personally I can stand Netorase(cuck) if the MC is such a piece of shit I want better for his LI... NTR is harder for me to overcome, cause it rarely finds a "nice guy" stealing the girl from either an asshole or a loser... NTR is always some bigger asshole or "bad guy" stealing, with some of the stupidest writing imaginable...
My favorite example of why I dont really get into NTR arguments (in game threads, topics like this is fine) aside from thread bans and shit... is that I wont change my mind, just like I know I wont change the mind of those that disagree, so its a waste of time... Lets talk about Big Brother as a prime example... Max (the mc) is such a little shit... no arguments, you'd have to be a total self-insert maniac to think he's a decent dude... some people, especially the NTR-yay crowd think of Eric (the NTR rival in BB) as a sort of hero... this is utter BS !!!
Max is a little shit, thats been established... but Eric is fucking scum !! Max is pervy towards his family, and manipulates situations to get into their pants (except Kira who wants it)... that's his worse flaw... he never blackmails, he never rapes... Eric is a "hustler" a man that goes around seducing dumb women, and cheats them out of their homes and money before tossing them to the streets as hookers... I'm sorry whats likable about that piece of shit ?
You dont need to self insert to SEE which of these two males is worse...