Uh, what?
The fear aspect of MHA is a completely different ability that isn’t linked to quirks or power level or anything. It is linked solely tot he willpower of the individual and enforcing it upon others.
Stain put fear in both Endeavor and Gran Torino, both characters who could easily defeat him. This was not a fear born from “oh no the serial killer is scary” or some ridiculous feat Stain did prior to even REMOTELY make them scared of him. It is attributed to his willpower and strength of character. His conviction was so strong that he made it a tangible presence that struck irrational, paralyzing fear in characters that had no business being afraid of him or even knowledgeable of his abilities to be slightly intimidated. Even people that JUST FOUGHT HIM were affected by this “presence.” He just got his shit rocked by three high schoolers and they nearly pissed themselves seeing him step forward not even at them. That is fear manipulation, not social influencing.
This of course then sets a precedent. There exists an ability in MHA that is wholely separate from quirks that stems from an individual’s conviction or willpower, rather than their strength.
We see this again from All Might when he fights Deku and Bakugo, where Deku says that All Night’s presence is comparable to Stains, and is why he runs from him so much. Of course, Deku is an All Might fanboy, so that can’t be fully attributed to fear manip on All Might’s part, hence why it is an example of social influencing. This is shown further when he, in his skinny form and just after getting blown out of his car, paralyzes two villains by telling them to move aside because of his conviction to help Deku. That is a more solid evidence of fear manipulation since they were resolved to fight him and remarked that they could beat him due to how weak he looked. They didn’t care he was number 1 after seeing his appearance, yet he paralyzed them with words alone.
Then there’s AFO, who is so obviously using the same style of ability Stain has that its ridiculous to claim otherwise. Making people who have no idea of your abilities or power besides a single showing hallucinate their deaths is not normal. That is not typical fear. That is supernatural as hell. And it’s not even something that can be put on as them being scared of his strength, because Deku directly says HE made them feel that fear. Not his attack or showing of power or defeating the heroes. AFO’s presence made them hallucinate from fear. This is especially ridiculous since Deku himself has seen and done stronger things than AFO’s air cannon, so there’s no reason he should have been scared of that to the point of seeing his death. Absolutely no he should lose this ability.
AFO’s fear Manip is further backed by Machia directly stating that it is his presence that makes people submit. Yes, he fights, but the “presence” of someone is what makes them Machia’s “king.” So even Machia acknowledges the supernatural aspect of the fear Manip.
And now, we come to Shigaraki, who literally has better showings than anyone else because he combines multiple. Shigaraki has the direct fear of COUNTERING A QUIRK with his simple gaze. The people under Trumpet’s quirk are literally being mentally amplified to not fear death and obey what he says without question. There is no reason whatsoever that anything Shigaraki does should override this ability unless he himself does something supernatural. They didn’t care that Re Destro was defeated, or that he destroyed the city. Trumpet told them to go down there and they were absolutely going to do so. They feel no fear. Several of them literally have run into death vs the League of Villains with no qualms whatsoever because of this quirk. His supernatural ability is making them do this.
Shigaraki overcomes this by staring at them.
That is such blatant fear manipulation it’s ridiculous. He stares at people amplified to not feel fear or care for their deaths, and they stop in fear.
This is compiled further during the war where he makes Deku and Bakugo hallucinate their deaths, similar to how AFO did at Kamino. He has the exact same presence as him, and it’s not due to his strength. Deku and Bakugo were MORE than resolved to defeat an All Might tier enemy. Deku particularly has been preparing for this for nearly a year at this point. He has every advantage going into this fight, all the drive and willpower to do so, and still he sees his death just from SEEING Shigaraki in the flesh.
One thing I would like to note however is that, despite seeing their deaths, Deku and Bakugo still were going to fight Shigaraki. Deku, in his hallucination at least, is even seemingly charging at Shigaraki to fight him despite dying, while Bakugo is aiming to blast him. So if anything, they should have resistance to fear manip for being subjected to Shigaraki’s fear manipulation and still trying to fight him.
Essentially: no, he should not lose his fear manipulation. It is a legitimate ability within MHA that is separate from quirks but VERY much present. The presence and willpower of characters has been an important factor since chapter 1 when talking about what All Might did to society, and has been a consistent theme of breaking limits and awakening to your true power. Trying to state otherwise is simply wrong.