It took a long time to move from the old component input over to HDMI. The main thing that drove it was the SD to HD change. You needed HDMI to do 1080p (I believe, IDK that component ever supported that high of a resolution).
Moving from HDMI to display port is going to be the same issue. People already have all their favorite HDMI devices plugged in and setup for their TVs.
You need a feature that people want which HDMI isn't or can't provide in order to incentivize a switch.
For example, perhaps display port could offer something like power delivery. That could allow things like media sticks to be solely powered by the TV eliminating some cable management.
It already does. A guaranteed minimum of 1.65W at 3.3V is to be provided. Until very recently, HDMI only provided a guaranteed minimum of something like 0.25W at 5V.
5W is what I'd think is about the minimum for doing something useful. 25W would actually be usable by a large swath of devices. The raspberry pi 4, for example, has a 10W requirement. Amazon's fire stick has ~5W requirement.
Sure. But it's ~6.6x more than what HDMI has historically guaranteed. It's pretty obvious to anyone with two neurons to spark together that the problem here isn't "amount of power you can suck out of the display port". If it were, DP would have swept away HDMI ages ago.
Nobody said it was.
I gave that out as and example of a feature that DP might adopt in order to sway TV manufacturers and media device manufactures to adopt it.
But not for nothing, 0.25W and 1.67W are virtually the same thing in terms of application. Just because it's "6.6x more" doesn't mean that it's usable. 0.25W is 25x more than 0.01W, that doesn't make it practically usable for anything related to media.
For the same sorts of reasons that made it so for decades nearly every prebuilt PC shipped with an Intel CPU and Windows preinstalled: dirty backroom dealings. But in this case, the consortium that controls HDMI are the ones doing the dealings, rather than Intel and Microsoft.
"But Displayport doesn't implement the TV-control protocols that I use!", you say. That's totally correct, but DisplayPort has the out-of-band control channel needed to implement that stuff. If there had been any real chance of getting DisplayPort on mainstream TVs, then you'd see those protocols in the DisplayPort standard, too. As it stands now, why bother supporting something that will never, ever get used?
Also, DP -> HDMI active adapters exist. HDR is said to work all the time, and VRR often works, but it depends on the specifics of the display.
I thought audio might be the reason, for as far as I can tell, displayport supports that too.