Rated shackles - what are they for?

The recommended minimum basic recovery kit is usually a snatch strap and two rated shackles. I've carried rated shackles around for years and used them occasionally to join a Tirfor, tree trunk protector or winch extension strap etc. So yes they are very useful with this other equipment in non-snatching operations. But I have NEVER used them anywhere within cooee of the snatch strap and can't imagine that anyone ever should, especially not to join snatch straps together. Not really keen on having one of these little suckers slinging at me at a million metres per second if something goes twang.

Now sure, some people might not have hooks or tow bar tongue on their vehicle to connect a snatch strap to, but even still I think it would be dodgy to use a shackle in any snatching operation.

So to my question. Is the reason why carrying rated shackles is recommended as part of a minimum kit is because when you get stuck somewhere, you can say to the dude with the winch, "Oh no, use my shackles." Or is there some other reason that just hasn't dawned on me.

MikeyS