There are two issues that should be separated. The first is that there were (and probably are) foreign spies in industry and government. That's damaging and they should be removed. The second issue is that those given the power to find and remove spies can abuse it. That's also damaging and should be prevented.

However, that fact that people abuse their power doesn't mean we should stop looking for spies, or that all spy hunting is a form of Mcarthyism.