but thats exactly whats going on around you, you just fail to see. MMORGs are extremely popular yet, they ultilise only a small fraction of modern CPUs and GPUs, pretty much what allowed Runspace to port easily to hmtl5. My 7 year old iMac was able to play Dota 2 which has been released quite recently.
You make the assumption that most users want apps that take full advantage of CPU and GPU, that assumption is wrong. Users want apps that are either fun or useful or preferably both. If we talk about 3d artists sure they will want a 3d app that can squeeze as much it can out of everything, but then that does not mean they cannot benefit out of web apps.
The average user though does not really care, he loves facebook, he plays games which according to your criterial are crappy as hell and does stuff that dont even remotely tax the CPU and GPU.
The reason why the web is slow, and yes its slow is because so far there was not so much demand for fast web anyway. But things are changing all the time, a web browser was just a thing to display static ugly web pages , modern browser can do a ton more because developers want to push forward. Who would think that the modern web browser would offer not one, not two , but 3 different technologies (WebGL , SVG and Canvas) that are GPU accelerated. It also means that web browser have become incredible more fast with the introduction of those new technologies. And is certainly will continue to get faster and faster.
And most importantly people LOVE the web. Take a look at Github, it does stuff you can as well do fine with a desktop app, you could argue its potentially way slower using still experimental / immature technologies, yet tons of people use it. Why ? People love to stay inside their browser.
Would you prefer to edit your 3d mess inside blender and then upload it, or directly edit the file inside your browser and reupload nothing, instant save, instant update in your website or web game, especially if its a small quick edit ? add to that the fact that you can edit that file from anywhere , any kind of device , anywhere in the world and you have a pretty tempting package. And if you do prefer doing in the first thing, how about all other people. These kind of web apps are not toys they are becoming increasingly popular and more and more companies prefer web apps to destkop apps.
You even tried to convince me that web technologies are more accesible from desktop than they are from web. Take even the simplest example, how easy to embed a youtube video inside blender and how hard inside a web app. For a web app/ web pages its a simple copy paste of few lines. There was a talk actually to do just about that for blender, and even provide links to blender wiki, but all that remained just talk. Your arguments fall down like a dominos.
Exactly !