I understand what you're getting all, and all I can say is... Actually I don't even know where to start. I
am a big Firefox advocate in many ways... I've been on the Mozilla bandwagon since they were numbering releases as M1, M2, M3, etc. I think I started using Mozilla at about M2 or M3 or back in like 1999. I don't take the idea of abandoning Mozilla lightly, but by the same token... I have too much going on, and not enough time, to desire to jump into the Firefox code myself and start hacking. My perception is that it's a huge, complex code-base, that would require a lot of historical domain knowledge, and/or a huge effort in time to understand, before one could make a meaningful contribution.
Coupled with the attitude of a lot of the top Mozilla leadership have demonstrated over the years (that is, arrogant, dismissive, abrasive, and unwelcoming), I don't feel much desire to jump in and help, as much as I'd otherwise like to.
Then Chrome comes along, and - for whatever reason - doesn't seem to have the kinds of memory issues that Firefox has become notorious for. It's awfully compelling to say "let me just use this thing that just works, as opposed to fighting with Firefox."
My personal and probably bias experience is that I have never felt a memory issue. I tend to run a lot of add-ons and I only rarely keep a lot of tabs open because I prefer to follow a pattern of opening up a bunch of things then working my way back down to zero.
To be fair, this is part of what makes this difficult for the FF team. There are always people like you who say they never see these issues, and there are always people who do see them, and are so frustrated with them that they give up. And there doesn't seem to be much rime or reason to the whole thing. I've heard the "bad plugins" explanation before, I've heard "you don't understand the output from top," I've heard "it's not a memory leak, that's by design... it's the way we cache images," etc., etc. But at the end of the day, for some people, in some releases, Firefox has consistently had a problem with sucking up, and holding onto, memory like it was going out of style.
For a while, when the going word was "it's memory fragmentation that's causing the problem" they did seem to make a lot of progress. I remember a bunch of FF 3.x builds over the span of a few months, where the problems did seem to go away (or at least mostly). But somehow they always seem to come back eventually.
I dunno... I'm rooting for the Firefox devs to get this figured out for once and all one day. And if they do, I'd probably switch back to Firefox. But to get back to the main point of this whole discussion... I'd rather see them spending their cycles on this issue, than adding features, building an OS, and all this other stuff.