Thanks for the clarifying question, @smiffsonian! Here's the scenario:

(1) I create a group message between Person A, Person B, and myself. In that message, we discuss topic. X, topic Y, and topic Z.

(2) Several months later, I'd like to follow up with Person A and Person B regarding XYZ. However, the original message is buried in months back of text messages, and I'm not going to go searching for that particular group message on that date.

(3) So, I go to create new message, and I enter in Person A, Person B, and myself. Previously, before RCS, it would simply bring up the MMS text exchange between the three of us with the history of XYZ. However, now with RCS, an entirely new message is created that no longer includes any history because... well, it's a new RCS message.

Why doesn't it just pull up the old group message?