First of all, it's not a low end PC, it's an expensive gaming-dedicated rig barely a couple of years old. The amount of resources browsers consume is just ridiculously high.
Second, the argument that browsers should use all the resources and ram available in the world only holds if your computer is dedicated to web browsing. This is quite obviously false - I shouldn't even have to give you my case as an example. PCs are general computing machines.
Web browsers are too hungry for what they do. Not every tab is meant to run a full blown web app with webgl and megabytes of javascript code. The point I was making was that what I'm not able to do with Firefox/Chrome, I'm able to do with vlc. That is preposterous for something that wants to be "the future of the desktop".
I can do all of that at the same time as is...