Dim isn't anywhere near right
You don't need to understand encryption at any level to understand why breaking it isn't a good idea. You just need to have a brain and a small amount of logical thought.
When transacting services online (let's say buying something), you need encryption to secure the transaction and provide non-repudiation. Otherwise, everyone can just insist it wasn't them. Obviously, encryption doesn't do it all, but it does the secure communication bit. So, therefore, if you allow anyone to break the encrpytion, every transaction becomes questionable. Bang goes your online economy!!
Now, that didn't require any thought beyond that found lurking in the average pond. All goes to show that Amber Rudd is not the missing link, but something far further back. Perhaps she's just crawled out of the primordial soup. If she keeps getting in, says something about the voters in Hastings and uselessness of our electoral system.