Karplusan Yeti hasn't been in print since the days of Ice Age back in 1995 and 1996. When the card was more commonly around, many players gave the card only a casual glance and missed the yeti in the process. (This is a yeti we're talking about though, so that seems pretty appropriate.)
In this enlarged version of Quinton Hoover's piece, it's a lot easier to see what's going on. (And that flavor text makes a lot more sense too.)
The players may not have been the only ones that missed what was going on in this piece however. Whoever picked out the packaging art for Ice Age may have made the same mistake, leading to what may very well be the only case of Magic packaging featuring the "wrong" part of a card's art!