People had completely unrealistic expectations going into this, and now that those expectations haven't been met, they're jumping straight to “he's a bust” or “he isn't an NFL caliber QB.”
The Titans didn't have the No. 1 pick because they were a good football team. They didn't have the No. 4 pick for the same reason. Cam was throwing to guys last season who probably never should have been on an NFL field, but that's the situation he was dealt.
On top of that, he had to deal with a midseason coaching change and is now learning a new system under his second HC and OC. The surrounding talent hasn't exactly made a massive jump either.
And let's not forget the obvious, he's still learning how to play quarterback at the NFL level while being thrown into the fire, and he's doing it with a skeleton crew around him. There isn't much room for error when you're learning the speed and complexity of the league without much help around you. People make mistakes, and because he is the #1 pick, it's all his fault and his failure.
You can't evaluate a young QB in a vacuum and pretend all of that doesn't matter. If the expectation was that Cam was going to walk into a bad roster, adjust to a new coaching staff, elevate mediocre talent and immediately look like a franchise QB, that's an expectation problem, not necessarily a Cam problem.