It came with its own remote right? So not sure I would call this 'went way south' just because the Xfinity remote doesn't have codes to work the TV. That's a bit harsh, especially considering it's an Xfinity issue.
At most I would ding them for not using common codes that LG, Samsung, Sony, etc. use.

The bigger problem is:
1) We don't have any cheap, minimalistic, well-laid-out, learning remotes anymore on the market. Those went away years ago now.
2) Everybody wants to use the stupid voice control remotes. And the big control companies (URC, RTI, Elan, C4, Savant, Crestron, etc.) STILL haven't got off their arse to put mics in their remotes and create modules in the software, to work with these devices.