As for the engadget link, why not link straight the source:
I used to do it because I had no choice (alternatives are way too expensive than what I can afford).
*edit: Forgot to mention also that ad blocking aids tremendously in making the internet more usable on underpowered machines.
There's a big difference between Chromebook and Linux/Pi/etc world of hardware/software experience for any person. You can throw a Chromebook to anyone and you wouldn't have to care about it. But try imagining the idea of giving Linux type OS to anyone...we know what happens next.
This is one reason why tablets (particularly starting with iPad) became popular among average crowd.
And your second point is almost moot since Chromebooks run on top of Gentoo Linux of all things.
What hobbles the web on older hardware is not "2-4GB" but very slow processors (having to handle all that advertising Javascript, over-animated UIs, and bloated front-end frameworks).
^ This, as someone else said in this thread - javascript is the new Flash of the web. At least in the Flash days, many web designers were descent enough to include html only versions. When I'm using my old laptop with js turned off many pages become unaccessible and web makers don't even realize that so many people in the World can't afford buying new computers.
As I write this my system is consuming 440MB of 4GB, and I have many other (mainly source code) files open which I'm also working on.
1) Find something to do with a Pi
2) Instead of buying a Pi, run Pi infrastructure software on an old laptop instead
If browsing doesn't work on an old laptop (although it does, but for the sake of argument...) then the bug is observed after step #2 but the actual failure location was in step #1, when "I wanna browse the web" somehow led to using a Pi to do it.