Uh, actually it does. Amateur means you're untrained and unskilled. Professional means you've had training, which develops and teaches skill, and you're good enough to be paid to do it.
Training means nothing when you don't use it properly. Fact.
Such as? Also, do you even know the skills required to be a good critic?
Take your pick from the ones who breach their so called professionalism to insult people for their tastes. Or maybe the ones who believe that an opinion can transcend it's subjective nature due to a college degree. Ebert's lashing out at Armond White over difference of opinion is a good example of both in one instance. I understand the requirements to become a professional critic, but being one means you need to keep yourself grounded on two simple rules:
1) Remain professional in practice, not just in designation.
2) Realize that your opinion is no more right than any other.
Rotten Tomatoes isn't a review site, it is a review aggregate site. They collect individual reviews and display them all, and give a work a rating based on how positive and negative the reviews are.
I'm aware of what Rotten Tomatoes is. What you fail to grasp is that aggregate review sites encourage critics to judge along the same lines to avoid criticism from their peers. Critics have been removed
from RT because they went against the norm. That is not criticism, it's a popularity contest.