It's just become a meme among tech enthusiasts (on Reddit, HN, etc) and tech journalists that "blue bubbles" are a real social problem. The origin of the meme was this amusing post by Paul Ford 8 years ago [1]. They took it and ran with it for their own purposes. For some it was to explain away the iPhone's success versus Android and for some interested actors like Epic it was part of their antitrust campaigning to illustrate the "lock in" effects. It however was never a social problem in the real world (more than, say, young people feeling depressed about seeing their peers' manicured lives on Instagram) or the reason why iPhones sell well (you only had to look to China, or now India, to see the success of the iPhone in places where iMessage wasn't the dominant messenger).