The bad guys know where to find solid open source crypto for their cloud backups and whatnot. Therefore you know this is not about chasing the bad guys. It's about keeping the Average Joe under the thumb.
It'll catch the bad guys who don't know what they're doing, which is a pretty big percentage of them.
I don't know where the belief that all criminals are tech experts comes from; the popularity of cool-looking "encrypted" phones as opposed to actually encrypted apps like Signal should have long dispelled that myth.
I'd argue that the opposite is probably true, people who think that crime pays are less smart and more impulsive than the average person, and hence less likely to think about things like this.