Although I believe that was Microsoft's fault, but Google shouldn't have copied it. I've lost more data to that than any web browser bug over the years. Fortunately Chrome had an extension that let me turn it off!
Is the back that backspace goes back, or that the browser doesn't store text you've typed in a textarea?
And even Opera tried to keep that too, at least in many situations, to keep the history an actual history and you'd switch through snapshots of the DOM+state--at least that's what it felt like, I'm not sure that's what it really did, but I guess it helps with speed, too. A webpage generally isn't supposed to move or change at all unless you're interacting with it, so really after it's rendered, flipping through history or tabs should be instant, even on an old machine because it's just bitmaps, really. I remember a while ago there was an article here that sort of explained why this couldn't be done or didn't work for some reason, but it was a tradeoff to get some feature that, given the option no one in their right mind would trade for instant history and tab navigation.