//Is This What Brexiteers Wanted?//
I imagine it's not what they wanted. But, certainly from my perspective, any attempt at disruption by the French must be entirely expected and anybody believing there would be none must be deluded (either that, or they've been listening to too many politicians, which is the cause of many of such problems).
It is the job of the French to staff their borders appropriately and these delays are caused by French staffing inadequacies. They knew, in June 2016 (i.e. six years ago), that different arrangements would be needed to deal with cross Channel traffic. It's no use saying "it's because of Brexit". It's because the French have failed to adapt to the new requirements, despite having six years' notice. Other countries deal with life as it is, not as they would like it to be. The French should do the same.