Heck, I've used it myself.
But it always makes me laugh a bit. It's the knitter's equivalent of "Drive Carefully". (When offered this helpful piece of advice by my Mum, my middle brother would always reply "Oh, ok", in a slightly surprised tone of voice. As if to say, wow, I hadn't thought of that, thanks.)
I think every knitter would agree that it's good to bind off loosely, just as it is to drive carefully. But it's easier said than done.
The very nature of the standard cast off is that that it tends to be tight... the process of lifting the first stitch over the second causes it to tighten up.
M., a very seasoned knitter, was swatching yesterday for a new project. Her swatch is a perfect example of something I see all the time..
Even stitches, a nice relaxed cast on. But the swatch isn't square - and very obviously so - because the cast off edge is tight, and it pulls the stitches in.
There are special cast offs for special situations: the Russian lace (third one down on the page), for lace; Jeny's Surprisingly Stretchy, which really comes into its own for toe-up socks, and EZ's sewn bind off (last one on the page), which is a bit fiddly but worth it for garter stitch edges in lace.
These are terrific, and immensely stretchy. Too stretchy, in fact, for everyday purposes. Too stretchy a bind off causes the opposite problem: a flared out edge that won't lie flat.
But often, when you're knitting a straight piece, you really just need a little bit more stretchiness - and the simplest way to get that is to use a larger needle.
That's it. Just use a larger needle in your right hand to work the stitches on the cast off row. And not just one size - several sizes larger. For example, when I'm binding off a piece worked on 4.5mm (US 7) needles, I will use a 6mm (US 10) needle. This makes the stitches too big, but then when lifted over, they snug down to a nice and appropriate size, while keeping them even.
Simple and magic - my favourite kind of knitting trick!