That logic is all fine and well, but that requires GitHub to determine if a takedown is valid or not. And if they determine incorrectly in a case, they’re open to damages in that case.
So, is it worth it? Or is it worth just letting the parties figure it out?
If the DMCA is truly invalid, a counter-claim can be filed. If the other party doesn’t want to file one, I guess GitHub wonders why it should keep the content up when the creator doesn’t have faith in it.
Obviously I note the possible flaw in the above logic, in that there’s a difference between an individual developer deciding it’s worth starting a legal faff with a big company by filing a counter-claim, verses GitHub doing it, but their service would go broke dealing with legal requests otherwise.
Correct way to deal with this is through your lawmakers, not saying Microsoft should foot the bill for a broken law.
To the extent that their core responsibility is hosting code, it is their responsibility to determine if some claims are valid.