Mass-market compatibility.

It's already difficult to find TVs with four fully-compliant HDMI ports; often you'll get a TV with one HDMI 2.1 port and three HDMI 2.0 ports, and sometimes the 2.1 port will also be the only eARC port so you have to choose between high framerates/resolutions and using a sound bar. In other words, even with just HDMI getting a decent set of ports is difficult.

The idea of TV manufacturers also adding DisplayPort ports seems ludicrous to me - not because it's a bad idea, but because I can't imagine them going to the trouble if there's no tangible demand. At best I could see them replacing HDMI ports with DP ports because there's limited space on the motherboard, but that would still require the board to have both HDMI and DP circuitry/chipsets and HDMI/DP certification/testing.

Then you have a TV with, say, two HDMI ports and two DP ports - which, for most users, means "two ports" since 99% of people don't have any hardware they want to connect to their TV that supports DP anyway.

So basically unless we start seeing game consoles, AppleTVs, and Rokus supporting DisplayPort we won't see TVs supporting DisplayPort, and we won't see any of those devices supporting DP because they don't need to - HDMI works fine for them and it's sufficiently universal.

Maybe China's new HDMI replacement will take off over there and make its way into devices over here, but I'm not holding out hope.

My understanding is that the HDMI 2.1 port situation on TVs is, weirdly enough, a SoC limitation from a single vendor.

Almost everyone (apart from... Samsung and LG, IIRC) is using MediaTek SoC for the brains for the TVs, and they just seem to be unable to make one that has enough bandwidth for 4xHDMI 2.1.

AFAIK LG and Samsung still handle theirs in-house (and that's why LG was the very first "big" vendor to ship 2.1 at all, and they rolled it out to all four ports even on their midrange TV's in _2019_!); and it's common to see those brands have more 2.1 ports.

This should be getting better in 2025/2026 model years, since it seems MediaTek has finally managed to ship a SoC that does it; but it's ridiculous how long it's taken.

China's new HDMI replacement currently has no known benefit over HDMI in terms of protocol governance issues.