Many of these "incidents" are kept secret from the public, we will never know the real number.
On the other side saying that "communism has killed 100 millions of people " is a little bit like saying "capitalism has killed 300 millions of people".
it is just a poor pov ...
But i can understand for simple minds it is easy to regroup under a big name to have a simple representation, just like good&bad manichaeism.

so if you wear this kind of t-shirt, you will be treated by people with a minimum of history knowledge as a simple mind.