If I want to play a PC game in the home theater, I just go the opposite direction with the Shield TV unit.
It's really not as complicated and hocus pocus as you make it sound. It's no different from using an Apple TV's screen mirroring feature to put something from your iPhone or iPad onto the TV, which *gasp* people use every day. I'm just using it to play videogames instead of show off the selfie I took eating a cookie at Starbucks. Unplugging and hauling PCs and consoles around the house and stringing cables just to do something at another spot is something from the previous decade.
For instance, I'm sitting outside at my patio table right now because it's a nice day and doing some paperwork on my MacBook Pro. I felt like taking a break and foruming. But if I felt like taking an Xbox break instead, presto, I just opened an app and hit connect:
The above edge case conveniently ignores how unlikely the described scenario is for the vast majority of consumers. Again, this stuff which as you point out works now for you, is nowhere because nobody cares.
Steamlink is cheap but does it sell like hotcakes? No, Valve gives them away. Nobody cares except maybe the Tom's Hardware crowd about trying to make a console out of a PC.
If the office chair beats your living room for comfort maybe it's time for some new living room furniture? Maybe skip a six hundred dollar video card and put it towards a recliner?
I think you are really reaching for straws when I am supposed to appreciate the benefit of being able to take an Xbox break outdoors on your MacBook Pro. Do you always bring your controller outside too just in case you might feel like doing this? You are presenting examples here of things that people do not normally care about doing as if that represents an everyday value for the average person. Don't get me wrong. If you like doing that and it works for you, great but that doesn't make it a selling point for most people. Just because you can do something doesn't make it an ideal way of doing it. Allow me to demonstrate:
You want to play a game in your office and you have a powerful gaming PC. So you play a PC game on the thing.
You want to play a console game and you have an Xbox One X. You enjoy the comfort of your living room and do it.
You want to take a little gaming break while doing some work outdoors. You fire up some casual or other Mac game on your MacBook.
In all three cases, you take the path of least resistance which is normal human behavior. You don't need extra apps or hardware. The stuff all just works with zero additional steps. No Nvidia shield, no remembering to bring your controller with you outside, no added apps to install and zero compromise in quality - I mean absolute 100% zero. This is the way the typical person operates. It's why they rejected Steamlink in the majority.
The majority, the huge overwhelming majority is NOT you guys. I don't think you get that. This stuff sinks or swims based on the majority and they can't be bothered and they are not willing to pay for stuff like this. One more time, this would be everywhere now except for one little problem. It's a solution looking for a problem that does not exist for enough consumers to justify its existence.
On topic here, about Steam on Apple hardware, not PCs, Nvidia Shield or Xbox for that matter my entire point has been that streaming PC games to a television sucks because in most cases it does. One more time, if it was great everybody would be all over it. They aren't. That right there says it all. My suggestion in light of this and therefore also on topic is just get a fraking console if you want to play games on your TV. They are made for this and excel at it.