Not third party. We are finding out that third party USB c bricks are incapable of achieving 15w charging rate with MagSafe.The difference with some of those historical changes though is the switches were done due to being replaced with superior technology. Leaving a charger out is for totally different reasons as is leaving out headphones. Neither have been replaced with superior technology and the reasons were purely financial with a bit of environmental marketing spin.
One major advantage of this which I hadn’t considered before is Apple are promoting third party companies as these are now benefitting from sales of cables, chargers and headphones. Not sure that was Apples aim but it appears to be playing out like that.