The problem with the DMCA is that the anti-circumvention clauses are vague at best, and unfortunately it's easy for well-funded corporations to make claims against it.

There is nothing in the law that talks about the effectiveness of the anti-circumvention tech, so even if the tech is trivial to bypass, if that bypass is done via "unintended usage" (according to the rights holder, not you) then they can claim you are doing something illegal.

It's a shitty law.