Apple and Google are merely absolving themselves of being involved in the legal matters of others.
The third-party doctrine basically forces third-parties to be legally culpable for discovery. Google and Apple don't want to be legally responsible anymore, so they've pushed the responsibility for complying with counsel to the end-user.
i.e. instead of law enforcement going to Google and Apple and saying "I have a legal right to search X. Hand it over.", law enforcement now needs to go up to the person whose papers and effects are being searched and ask the same thing.
Had the founding fathers been aware that the notion that one day third parties would become responsible for the papers and effects for millions of citizens, it's reasonable to assume the warrants would have had to be issued in a way where the subject of the warrant would at least have a right to know they were the subject of a warrant. With third-party doctrine, the government got the benefit of issuing warrants to entities unlikely to protest because protecting the rights of others incurs a cost.
Third-party doctrine has been a civil liberties disaster because it decoupled the recipient of the warrant from the subject of the warrant. That decoupling has lead to a scenario that deprives millions of people the right to contest a warrant in court because they might not even know such a warrant was ever issued.
It's not like Google and Apple are taking away the government's ability to issue warrants. They are just removing themselves as a third-party. The government now needs to go directly to the person who possesses the phone and issue a warrant to that person.