I tend to mind-translate NTR and NTS as NTRegret and NTShared. (where Regret means "Fuck!! Why did I let this happen?" And Shared means "Fuck!! Agreeing to do this is Hot!!")
Yeah, I know I'm probably alone in this view...
It confuses me as to why NTR is more popular than NTS. More people get off to feeling humiliated and betrayed than having shared experiences with their significate other?
There are a lot of examples where a "game" starts off looking to be shared experiences and turns into beta cuck simulators because the audience wated it?
No kink shaming, and these are just fantasy. but why? is it just the bata cuck's "moan" louder?
These two thoughts/concepts are linked... The first is part of your answer to the second.
1. NTR is very broad, and there are many "debates" that spring up about what is and isn't NTR... Please, let's not debate it again here...lol Just pointing out that people interpret the NTR tag differently, not debating right and wrong...
Your differentiation is pretty good and a fair perspective to have. You're definitely not alone, even if people don't have it clearly defined for themselves...
2. Your characterization of NTShared is valid and relevant to why NTR is "more popular". The cuckold/hotwife fantasy, which may or may not involve "humiliation" or "consensual cheating", is featured in a lot of NTR, but the cuckold/hotwife can be NTS; this is usually when/why that fetish triggers the NTR debates... Doesn't matter what perspective you choose, the point is the "cuckold"/hotwife fetish is found in NTR novels. And with the lack of good "sharing" content, the consensual cuckold/hotwife fantasy is as close as NTR comes to "sharing"... So, NTR stories can draw in a broader audience by making the "cuckolding" consensual, or not...
3. The mistake NTR writers make, is as you suggest, they make the male MC "weak", because that's the "cheating/NTR" path "mained" in the story. The wife is fantasizing about sex with other men because the husband is "inadequate" in some way... Or, she gets "corrupted", or she's really a slut and just needs to let it out... And you're right, those types of stories get out of "control" for the "weak" male MC. "Sharing" is the actual fantasy, because that's not how it usually plays out IRL... Reality is, despite what many may think, what women say, or how it's portrayed; there is a strong correlation between "emotional connection" and sex, especially for women... So, if you give the go ahead for your wife/gf/LI to have sex with other men, the risk of her developing that "emotional connection" with the other guy, displacing "you", is very, very high... And that doesn't even factor in if she enjoys the sex more with her "lover" than the husband/bf...
4. Is the "beta cuck" louder? Yes, partially... They certainly seem to be more willing to throw money away...lol Seriously, there's a JOI simulator game, dev pulling in over 20k monthly on Patreon... like WTF?? I mean, the little customizable succubus is cute and all, but damn...
The other factor, that "beta cuck" story is "easier" to write... It provides an easy, quick plot device for the wife/GF/LI's motivation to "cheat" or be "corrupted". It can appeal to more than one audience (the "alpha" trying to "steal" the girl or more likely just fuck her...lol) as well as the "beta cuck" fantasy folks. And with just a little tweak to make it consensual, you have some "sharing" fans reading it... And along the lines of what Johnny said, there is a pretty big audience (that almost seems to dislike women) that really enjoys "corrupting" the woman, especially fem protag stories (Anna, Steps of Debauchery, etc)... And the NTR stories with paths, the reader is generally in control of choices for the FMC, soooo, they get that element of turning her into a total slut who's willing to jump into bed with anyone, including dirty hobos...
I swear, it sometimes seems like dudes want to punish/degrade the female MC... It's weird to me...
Yeah, there are people who are into the humiliation part. I don't know if they are "more", or most. But combined with those who like to do the stealing and corrupting, that's a very sizable audience that a dev can appeal to...
Annny way...
The answers, reasons aren't simple.
They're complex and nuanced.
Thankfully, Johnny made this list to help filter out some of the "trash"...