To be fair, HBO Go and HBO Now were technically two separate products. HBO Go was the TVE app that allowed for linear channel viewing and came with the HBO CATV subscription, and HBO Now was the original name for the OTT app that is now HBO Max.
While this is true, it was always rather a pointless distinction, since the two apps served essentially the same content -- you were simply steered to use one or the other depending upon how you
paid for that content. I'm sure that all had to do with their legacy media licensing deals and big media desperately trying to fight against the a-la-carte business models that "cable cutters" desperately wanted... but those two variants existing at the same time instead of sequentially arguably made this whole naming issue
more convoluted and confusing, rather than less.
Of note, though... Warner Bros/Discovery owns both HBO and Cinemax. I find myself wondering if perhaps they tried to leverage heavily into the "Max" naming in order to highlight the brand (and content) that they assumed had the broader appeal -- except that Cinemax content continues to this day to be licensed out to multiple other streaming services.
So, my wild speculation is that they had planned on bringing all of that content exclusively into the "Max" streaming service, but they either concluded that the existing licensing deals were more profitable, or they discovered that
cancelling those licensing deals was... untenable. Either way, renaming it back to HBO Max (and yes, maybe eventually to
just HBO) when that effort failed was really the only logical choice left, at this point.
But hey, what do I know? I'm just a schlub with access to Google and only slightly better than average Google-fu.