DMCA is a legal mechanism that the platform has to comply with. This isn't a case of a private company removing something that violates the ToS, it is a law that can be easily be abused by a third party to cause content to be taken down.
It's like if there was a law that said if you send a notification to a storage or logistics company that you think one of their customers has counterfeit goods in their storage, the storage company is legally obligated to destroy the suspect property, regardless of whether there is any evidence that it is actually counterfeit. Or even just, that company is no longer allowed to provide service to that customer, and is allowed to seize and keep any property they currently have control over.
I could also talk about how many of these platforms have too much power, and the lack of competition makes it problematic if they have control to censor as they please, but that is really a different topic.
It's like if there was a law that said if you send a notification to a storage or logistics company that you think one of their customers has counterfeit goods in their storage, the storage company is legally obligated to destroy the suspect property, regardless of whether there is any evidence that it is actually counterfeit. Or even just, that company is no longer allowed to provide service to that customer, and is allowed to seize and keep any property they currently have control over.
I could also talk about how many of these platforms have too much power, and the lack of competition makes it problematic if they have control to censor as they please, but that is really a different topic.