> You can now do everything you could do in Flash, with CSS.

AND JavaScript.

With Flash, you just needed to know Flash. With HTML5, you need to know a whole lot more about DOM manipulation. If you're animating SVGs, that has its own markup and learning curve.

Flash could also do 3D animation, which CSS cannot. You need to know WebGL and a library like three.js for that to be workable.

By far the best WYSIWIG animation tool I've used is Tumult Hype for Mac. It handles the creation of all the JS-based animation triggers through the GUI. I hope there will be a WebGL version of this that is as easy to use.

> Flash could also do 3D animation, which CSS cannot

Saw a few Codepens over the years[0] where people managed to rotate 3D cubes, all done entirely with CSS. Of course if you needed to interact with the cube you would need JS, but 3D can be achieved with CSS alone, it's just a very hacky way of doing it.

[0] https://codepen.io/mehra_as/pen/KRKPBq

This is a CSS only 3d thing I did a while ago as an exercise. Its a bit buggy but still pretty neat https://jaygles.github.io/city-block/

You can do interactions with hover, [hidden] check boxes, focus and even anchors.

Someone made the new iMac with CSS

That article is about rotating 2-D shapes on the z-axis (3-D plane).

An image of a cube in an HTML document will look like 3D without any transforms applied. However if you try to rotate that image on the Z-axis, it will warp, clearly showing that it is still a 2D object. There are other necessary aspects of 3D such as camera angles and dynamic light and shadows, but that's outside the scope of what you'd expect to be supported in the official CSS spec.

HTML and CSS don't support 3D shape manipulation and motion. WebGL is needed for that.

However, Flash was really easy to get into. You didn't need any programming whatsoever if all you wanted was a vector cartoon. And you did need to copy-paste some ActionScript if you wanted a fancy-looking navigation bar. Current web lacks this ease of authoring, so I wouldn't say "you can now do everything you could do in Flash".

Flash also felt more like a proper application framework. Web still feels like you're working with an extremely advanced word processor.

Both of those block usage on mobile device. Is this irony?

Try spoofing the useragent, or if your browser supports requesting a 'desktop version', then use that. I wouldn't use a phone to code though