I agree to some extent, but there's a heavy dose of context here.
First off, it's obvious that Pep in calling a conservative and measured offense that relies of short passing and measured ball movement. Is that because of Mills? Is it because he wants to limit mistakes because of Mills inexperience? Is it because we have below average WR1/2/3 talent? I would say possibly all of the above, although Mills had the best 20+ Passer rating in the entire NFL last year, so I have a hard time believing he doesn't trust Mills putting the ball downfield.
In the end, the team is not going to score a lot of points because it is not designed to. It's designed to be a 1990's style, ball control short passing offense with the occasional vertical strike. No motion or creativity whatsoever.
And even though I'm bullish on Mills arm talent and overall starter viability, I'm under no illusions he will even become Rodgers, Mahomes or Allen. My baseline prediction, if he's developed properly, is someone like Derek Carr, where he shares a similar build, arm strength, game fluidity and approach, although Carr is obviously better right now.
Some fans may think that's not enough, and that's fine. But if the baseline is getting the next Mahomes or Allen, well we could be waiting a long time for that and spinning though a multitude of QBs to find the golden nugget.