Weakening encryption makes it easy for people in power to take advantage and, for example, installing software on the computer or router that let's them monitor what the victim in this situation does or says online. This doesn't even have to be a government or corporation, it could be the person abusing children. Weakening encryption gives software the ability to do that. E2E encryption strongly hinder that if not stops that ability. Not everyone grows up a loving environment. I urge you to look up statistics regarding the relationship between the abused and abuser in the majority of situations.