While I agree with the fact that he should know the playbook and he should sort of have established some chemistry with the offense, practice and/or preseason games don't come close to what he will be doing/seeing tonight. Not to mention the pressure that was created due to the circumstances surrounding not just this week, but ever since Love was drafted by the Packers. One would like to think that having some quality players on offense around him will help offset his inexperience, but I don't think it will fully makeup for it.
You are correct, Trevor Lawrence, Zach Wilson, Justin Fields and 100's of other rookie QB's that haven't fared that well could point to the offense and say "I wasn't working with much". However, I think it goes way beyond that and it comes down to the talent and skill level of that QB, as well as his experience. Maybe if Love had to play the rest of the season, with these same guys on offense, we would start to have a decent idea of what we have by game 6 or 7.