Flex Time?

The only thing there is that might do what you want (up to a point...) is the Automatic Speech Aligner. You get to this by selecting two clips that you want to align, and right-clicking - it's in the list of options. It's really intended for speech, but actually it works quite well with singing - YMMV.

The reason that there isn't much like this in Audition is that really, it isn't music production software as such at all - it's an editor. The debate about this has been run ad nauseum but the upshot remains the same - no requests from the big ticket users so no development time available - despite some of the developers being quite keen on the idea. And even if some of the tools were added, it would always be playing catch-up. So it's moving more towards audio post for video - which to be honest is why Adobe bought the software in the first place. And the company that produced it. And the staff...