I don't know who is the guy you are speaking of, but on a cold boot you have about 520-530 Mb of RAM available ...
I'll find him....went on and on and on and on for several weeks....you're absolutely right, I'm seeing about 545Mb available, only 230 wired---so, including active almost 75% overhead. Active RAM can be redirected to what you're doing
Please go to Apple's own website and tell me your experience with any device running iOS 7 firmware. After it loads (if it loads) try to double tap/zoom in:
http://www.apple.com/iphone-5s/features/
On it now---looks, loads and works beautifully....in landscape. (I was surprised how quick it loaded with your comment). In Landscape, there is no 'zoom' in. As it's already perfectly centered.
In portrait, I was able to crash it on the third try on my Air, second try on my Mini. Now...is this the ONLY place you've found this? Weird...I visit all the ridiculous sites (for code and java)---from Ars to T/C, Anand to Facebook. Never an issue. There's ALWAYS going to be a site that'll crash ANY browser. It's hard to believe this would be the 'only' one....but, sure, in Safari it will crash one out of three times in portrait, not at all in landscape....nor on my 5s.
Tried site on iCab. Loads perfect, fast and doesn't crash....in landscape. Does in portrait
Tried site in Chrome, almost immediate load....perfect in landscape, fast scrolling....and really the FIRST time I did the 'cruise' to check out the entirety of the content. Apple F'ed up that page. It's BAD!!!! There are about 4 dozen high resolution pictures, ton of content, links and as mentioned above, EXTREMELY dependent on Java.
That's an extremely BAD example though....a TON of interactive and scrolling content....after looking through, there may be a HUNDRED pics---lol, if you DO want to enjoy this exact page though---turn your iPad in Landscape and it works JUST fine!
LoL----Good job though finding a singular example on of all sites....Apple's!
ARS, Facebook, T/C....they all FLY now, lots of optimization since last year's release of HiDPI displays. I've been pleasantly surprised both by the browsers and the site coders over the past 18 months. As an early rMBP adopter, initially it was pretty ugly....things have changed a LOT!
Come on Apple though....That is a helluva loaded page...and in landscape it's a Beauty!