Yeah, I don't know anyone like that and I am skeptical that a significant amount of people exist who do. This article is pretty lacking in substance. I certainly know people who strongly prefer iOS personally and frequently remind everyone of said preferences, but you could say that about video game consoles.

I know multiple people who refuse to communicate unless it's on an app like Signal or Telegram, but I don't know anyone over the age of 17 who cares that my bubbles are green instead of blue. And even if I did happen to know people like that, I still don't see "well some people will find literally any excuse to be exclusionary" as a good argument for iMessage locking users into their ecosystem.