I steal content all the time. It is wrong, but I do it anyway. If I create content that can be copied in a frictionless way, I know it will be stolen, I will expect it and I will be pissed.
What do the people who are criticizing udemy want them to do? Bias towards dropping all speculative content? That would make it very hard to onboard new users, lead to abuse, and lead to dead-links and ephemeral content.
Do what they are doing now? Trying to take content down that is known to be copied, especially when it is pointed out publcily. Obviously, it is good from a biz standpoint they want to make money, protect their reputation and not have to hire a ton of mechanical turk workers to prowl all social media.
so what do you want? The world could use an awesome answer to copywrite issues, but there is no easy answer, it is hard to automate, and that is just a reality that we will have to live with for a while into the future.