I'm not faulting the Moz developers per-se, just saying that - as a group - developers should not just throw up their hands, shout "RAM is cheap" and then be totally cavalier about how their programs use RAM. It's a refrain that has become, IMO, all too common, and I think it's harmful.

Sure, Firefox, and every other program should use as much RAM as it needs. But we should be mindful of keeping that need as low as possible, at least for any program that falls into the category of "runs in a multi-program environment and probably won't be the only program running from a finite RAM pool".