Why don't we see Denobulan's in other iterations of Star Trek?

The real world reason is obvious; Denobulans weren't created until Star Trek: Enterprise came around and they were an original species. But where is the fun in that? We as Star Trek fans love creating and theorizing in-universe reason for mistakes, retcons, and absences all the time. So why don't we see Denobula or Denobulans in the 23rd and 24th century?

In this episode, we do a "what if" scenario featuring Phlox's home planet as well as a lightning round of "what if" possibilities on a vast array of Star Trek topics, all submitted by listeners like you.