Bad calls are part of the game, just like bad blocking, drops from receivers, and a QB’s missed opportunities. Every person on that field is imperfect - that is part of the game.
A fault lies in the team’s inability to score on plays other than the said non-call, which allows the team and their fans to claim that they were robbed by poor officiating, when, if they were a better team and performed better, that call would not have mattered.
I got curious about there being a penalty for the helmet-to-helmet infraction that you mentioned. That appeared to be a legitimate football hit. So, I searched and found that there appears to be no rule against a helmet to helmet hit, as you claim. There is a law against lowering a head to use the helmet as a weapon:
https://operations.nfl.com/the-rules/nfl-video-rulebook/use-of-the-helmet/
If I’m wrong about the helmet penalty, please let me know.
See “defenseless receiver”