It's not "related to", it's "illustrative of" the pitfalls of market orders. The point was that even in highly liquid markets (i.e. Swiss franc), you can have sudden gap moves and liquidity fluctuations and a market order will just match against whatever momentary, ridiculous price happens to be there.

I would note however that after the SNB event many exchanges and brokers busted the trades that were done at extremely off prices.

A post-gap market sell on a gap up can end up filling pre-gap buy orders. And pre-gap market buys can end up being filled by post-gap sells. So people end up selling for much less or buying for much more than expected.