Some good points.
The issue with Brexit, through no fault of anyone, was the timing.
Soon after Brexit the biggest health issue for over a century occurred. Worldwide economies were struck down. Factories closed, output down, governments paying out billions to help the public but collecting minimal tax back, retail sales collapsing......everyone gets the point.
Then the war in Ukraine and the energy crisis caused by it.
Had there been a clean run of a few years following Brexit we would have had a clear view of the effects. As we didn't, we don't. Brexiteers and Renainers can argue until they are blue in the face but, at the end of the day, nothing can be proved either way.