What reason would that be?! What would be so horrific that would cause the demise of a manufacturer by empowering their consumers!? Let's take PC/Mac into consideration...
PC - Still the number one selling computing device. Consumers have access to BIOS, firmware, raw code, registry, base code, all hardware (ram, CPU, HD, Graphics card, etc) The consumer can if he/she decided to update, change, repurpose, etc.
Mac - VERY Small % of the computing market. No access to upgrades beyond a few hacks to change the HD. You order X ram you can't upgrade. In the enterprise market the ONLY reason it's popular is because of the OS vs Hardware as consumers/enterprise has zero access to customize.
You see, by empowering consumers, you get consumers on your side and they embrace FREEDOM to change, update, customize, verify...
That's why Denon, on their own website provides all of the IR codes, so people can customize remotes, etc.
So coming full circle, why not give them this lovely feature to verify HDMI cables!? As I said in another reply, it's a feature and selling point!
I can verify that the "supposed certificate" hdmi cable I bought off Amazon by a feature of my Denon AVR, heck yeah a selling point and feature that should be marketed!!
The percentage of users who use the Hex code to customize their remotes is far lower than you think- in fact, unless someone is just a geek or into computing, it's unlikely that they know what Hex is, never mind knowing what it's used for, how to convert to binary or octal. In fact, if you were to ask 100 people if they use any of the advanced features of their AVR, most would start their answer with "What's an AVR?". In the past, a lot of people who owned a stereo would bring their receiver in for service, thinking that the amplifier was toast but the most common reason it stopped making sound was due to the Tape Monitor switch being engaged. What does that tell you? Even now, if buttons can be pressed, they will be and that includes the ones that kill the sound. I have to talk people through that all the time, even if they have a universal remote.
WRT "certified cables", the problem with this is the fact that some manufacturers send their shortest cable, receive a 'Pass' grade and then their marketing department advertises their whole line as 'Certified'. If you want to know what works, ask a Custom AV installer- preferably one who doesn't work for a store that sells a lot of one brand that is expensive, uses batteries or sues people. The two companies I'm referring to have cost a lot of people far too much money for BS reasons.
I usually use Vanco HDMI cables. Why? Because they work, the price is reasonable, the short ones (10' and less) are very flexible and because they have small clips on the shell, they stay in place better than just about any others. They also come with lifetime warranty and unless they have physical damage, they'll cover it of it ever fails to transmit the signal. That's in contrast with Key Digital, who won't cover the cable I used in an installation that's three hours from where I normally work, had a three year warranty (which is supposed to begin as soon as I install & sell it) but had been in stock at a local branch of a national distributor for over a year after that part had been discontinued, instead of being blown out as a sale item. The guy in tech support told me that since it has four shielded wires, I could use an RJ45 end to terminate it and then purchase one of their HDMI extenders, as I would if I were using Cat5e/Cat6 cable. Now THAT's some good tech support! The fact that the center wire is stranded must have been forgotten.
I just googled 'HDMI problems'- came up with 26 Million results.
HDMI should never have been allowed to remain for as long as it has, IMO. It has been problematic for 16 years (it was designed in 2002) and that has only worsened because the demands on the system have been increased. These were never intended to be longer than 6 feet and they were supposed to be left alone after being connected. The plug is a terrible design, they should have been round, used a retaining screw/clip and they shouldn't be as stiff.
My point, and my personal experiences caused me to come to it as soon as I saw the problems, is that HDMI should have been abandoned before it ever went to market.