> You seem to be attaching too much significance to the color.

I'm not. That is what the Twitter OP indicated as the actual reason.

He was left out "specifically because he was on Android and turned the thread green" (sic). Or in the student's own words: "we would start a new group chat, and the group would realize I was the reason it was green, and they would start another group chat without me". Nowhere is mentioned that the degraded experience is the reason.

It could be that that the SMS experience is the reason when it comes to adults who are mature enough to leave the green/blue behind them but have a lot less tolerance for poor UX.

But for teens - which is what this thread is about - I fully agree with OP's conclusion that the social stigma surrounding the color is the primary reason.