The article is about end clients on residential and/or business lines. There is no reason for client-to-server communication to rely on STARTTLS on port 25.
There's also no reason to discount server-to-server SMTP on residential or business lines. Especially since this is part of the larger net neutrality discussion.
I worked at an ISP and no, net neutrality aside, SMTP on residential is bad bad bad. It should be permitted only at the customer's request, but probably won't fix the fact that their subnet is on a global spam blacklist.
The point of NN is that the ISP shouldn't get to make that decision. Even "allow on request" is very problematic because it's a slippery slope. Many people run SMTP at home mostly to receive mail, because the ISP is legally obligated to retain mail logs for law enforcement etc. (EU data retention law)
