It's definitely a myth.
It is true that many of the complicated knitting patterns for sweaters came from wives knitting individual sweaters to recognise their husbands should they drown while out on the fishing boats. (There are so many real historical sources for this I won't even bother noting them.)
However, the closest you can come to saying a particular pattern is linked with anything would be to refer to the style of knitting. For example, Fairisle knitting is a very distinct type of knitting 'cable' patterns but each person in Fairisle would knit up their own particular design.
(Well, they used to, at least. Now that island makes half of it's money from the ladies there knitting up a storm for export.)


With all of that said, the sweaters on that site are really very nice.
It's just a shame they felt the need to make this sort of thing up to market them.