I don't think there's this antipathy toward Frost, rather he was overhyped based on his CHL performance. If he had been seen for what he is, a 3C with potential 2C upside who needed time to develop and get stronger, there would be a different dialogue.
He clearly wasn't NHL ready in 2019-20 and needed a year or more in the AHL and a summer in the weight room, he got bounced around like a pinball and was a severe liability on the road where opposing HCs could match him up against physical centers. Then he lost a season to the shoulder injury, and was inconsistent during a chaotic season in 2022-23.
If Frost was "held back" it was because he was rushed to the NHL. Had expectations been lower, they would have been more patient with him. He wasn't TK or Farabee, who were better players at 19 than Frost at 22. Like Tippett, he needed time to develop.