[2021] Can someone explain to me how R6 went from counter terror to this?

Hey!

I'm pretty sure it's explained in Outbreak but essentially I believe Ash was first drafted in to assess what was going on in ToC as an expert. They had no idea what was was causing the issue and the possibility of biological terrorism couldn't be ruled out. It's Ash who asks Six to bring in some of Rainbow to tackle the outbreak and suggests recruiting the GIGN experts in Lion and Finka.

In Extraction a specialist branch in the form of REACT has been formed to deal with the situation.

I cannot argue that the Archaens don't feel out of place in a Rainbow Six game but it's been clarified that both Outbreak and Extraction are considered non-canon to the story of Siege and take place in an alternate universe/reality. Consider them "what-if?" scenarios.

I can say having played the entire game extensively that Extraction has more in common with the original 1998 Rainbow Six game than even Siege does. Suspend your disbelief on the Archaens and you'll see lots of classic Rainbow 6 mechanics and gameplay style. Slow, stealthy and tactical is the best way to play the game!

Thanks a million :)
AJ

The comment from /u/UpComin which contains a link to answer from the recent AMA is the best response to that question I think.