HDMI has failed to deliver for years, but remains the standard which is in place for consumer and a lot of professional electronics for decades now. I remember when Extron came in to our office and touted how they were doing everything using DisplayPort because it was the future. I looked at him, said he was wrong, and that he woudl be back in a few years with all the same products but this time with HDMI interfaces on it. He assured me he would not. He was wrong.
The headache is not that HDMI sucks. It's that it sucks AND it still has become a standard which is used everywhere, all the time, by everyone, with few exceptions.
The real headache though is the lack of proper implementation with minimum feature sets included. I would say that adding some 2.1 features to a device, such as eARC, should not allow for HDMI 2.1 to be advertised as 'supported'. Yes, it's confusing. That's the whole point. It's just confusing and stupid.
As well, HDMI still doesn't carry mandatory stereo along with surround sound at the same time. So, you can't get audio to a stereo set of speakers in another room without a receiver that performs DSP on the surround mix for stereo output OR the source changing from surround sound to stereo. Silliness, and it should have been right from day one.
That's ignoring the joke that CEC is.