The real reason why both continue to be developed in parallel is industry politics. HDMI is the product of consumer electronics companies while DisplayPort is from PC hardware manufacturers. For various reasons these two groups rarely cooperate. One big point of contention is royalties. The consumer electronics companies like standards they can charge royalties for, while PC companies like royalty free standards.
Since DP is royalty free, why wouldn't most consumer electronics companies push for it as well? Only minority would demand royalties, while majority would be forced to pay them. So why not ditch the patent encumbered standard if majority would benefit from it?
The consumer electrons industry is dominated by a handful of companies. Those companies also happen to be the ones who own the patents on HDMI. They control enough of the market that the smaller players are forced to pay up to be able to interop with the dominant companies' products.
Monoprice is selling 10' DP cables for $5 and 10' HDMI cables for $6. Maybe you need to find a new place to buy cables. Amazon Basics has a 10' DP cable for $12.
"Optional 8-channel audio with sampling rates up to 24 bit 192 kHz, encapsulation of audio compression formats (including Dolby TrueHD and DTS-HD Master Audio from v1.2)"
DisplayPort might be cheap, as it's royalty free, but one has to buy a cable dongle to convert it, as displays rarely feature a DisplayPort.
None of my business monitors, TV nor projectors have DisplayPort, but every notebook, discrete graphic card came with a DisplayPort - so they first thing is to buy another dongle to convert DisplayPort to HDMI or DVI.
Because native plain DisplayPort is only available on HP and some other Windows laptops (not sure about the state of the desktop GPU market), and it's rare as input.
The rest of the market - consumer Windows laptops, Apple pre-USB-C-crap-series laptops, gaming consoles, cable TV boxes, other home theater stuff on source side, as well as TVs and projectors on the sink side - speaks HDMI only.
DisplayPort is widely available on business-class laptops, gaming laptops, all modern discrete graphics cards, all modern integrated video chipsets (although not all motherboards/devices will actually provide a port), etc.
You're actually diametrically opposite of reality here: the only devices which do not widely support DisplayPort are cheap crap intended for the low-end consumer market, and stuff exclusively targeted at the living room market like consoles and media-stick PCs.
Even something as pedestrian as my old Thinkpad from 2010 supports it.
Every modern desktop graphics card has display port connectors. A common configuration is 3 display port + 1 hdmi, making hdmi the legacy connector. My five year old laptop has display port. It's not as rare as you think.
At least on desktop GPUs, you tend to get a lot more DisplayPorts than HDMI. You're lucky to get more than a single HDMI port, but three or more DPs are common.
No, the ports on the Macbook are PCIe + Displayport. The Apple displays are PCIe only. The parent was specifically talking about Thunderbolt. You aren't using anything Thunderbolt when you plug into a DP monitor.
