This is not related to net neutrality. Typically the way things work is that your end-user ISP is connected to a "Tier 1" or "Tier 2" ISP. Then the website you want to visit is also connected to an ISP in a similar manner. To get packets from the end user to the website, the traffic has to transit over the Tier 1 and Tier 2 ISPs. Those ISPs do not offer this service for free. To lower costs and potentially improve latency, many websites are happy to connect directly to the end-user's ISPs.

Imagine that your Internet service is just an Ethernet cable that goes to a router in a datacenter. This is Apple offering to plug their servers into that router. Now you can get to their servers without going out to "the Internet" via a Tier 2 or Tier 1 ISP. That is where the word "internet" comes from -- interconnected networks. More connections is more internetting.

This is all super common. Many big companies are happy to peer with small ISPs if they're already in the same building.

Edit to add: The edge cache thing that this article is about is similar, but not quite the same as what I'm describing. Instead of connecting you to their network, they just put some of their servers in the same datacenter as your network. Even less latency!