Sure.
Because it straddled all political parties, and all strands of political opinion from the hard left to the hard right.
Leading question. It's not what it would have had to include, but what it would have to have excluded. If it had excluded voices from all of the leading national parties other than those of the right wing, then that would have been a start. If it wasn't a campaign that simply reflected the will of the majority of the population, many of whom were traditional left-wing voters, then you'd have more of a case ...
The problem is that you are lazily trying to pigeon-hole Brexit. You are of the left. You disagree with the result. So, automatically, you assign it to your political enemies: the right. This is weak thinking, if it is thinking at all.
It seems to be beyond your understanding that Euroscepticism ran deep and strong throughout Britain, through all walks of life.