The Magsafe connector has, too.
As has MagSafe 2...
The original MacBook Pros had MagSafe, which was proprietary, but DVI for displays (open); later on they had Mini-DP or Thunderbolt The MacBook follows a similar pattern.
So once MagSafe was eliminated, Apple switched to non-Apple-only plugs, though since they were early adopters, it perhaps seemed like it was proprietary. However, Apple did not own (mini) DVI, (mini) DisplayPort, Thunderbolt, or USB-C.
The only Apple-only pugs are/were the old 30-pin iDevice connector and Lightning.
Gotcha, then why does new iPhone not have USB-C while new MacBooks only have USB-C?
As far as whether Apple should now migrate from lightning to USB-C, that's a separate question with tradeoffs on both sides.
There is a better universal alternative out there today and yet they continue to use Lightning port in iPhones.
They could have easily went with USB-C.
Apart from Lightning, which was created when no better alternative existed, I cannot remember a proprietary Apple connector in at least the past 10 years.