You posted three links to the android documentation that don't address sedev's point at all.
Your first point doesn't address the "falling back gracefully" part. The second part of that example, the ActionBar, which was introduced in ICS, IIRC, only has a community shim. Granted if you want to use a new API that may not have as much community support as the ActionBar, you either code one yourself (strengthening the sedev's point that you have to design the same functionality across multiple versions).
Your second point is even more off base. With the web's responsive design, I have to make one HTML file, and one CSS file, and if my design is sane, it works across all screen sizes. Your second link requires you to hand code different layouts for every device size which is hardly a solution - infact you are back squarely where you started. And I'm unsure if you actually read those tutorials but they don't even seem to have been updated since eclair. IIRC, you only had to deal with 3 sizes then - ldpi, mdpi, and hdpi. I haven't done Android dev in a while, but I'm sure the number of layouts have tripled.
If you really want to counter sedev's point, you should point to an app with the relevant code that actually does what sedev is talking about and not some links to the documentation. Everyone is already aware of the documentation, and if it actually worked as you said it did, we would not be having this conversation.