Don't jump to "selected for" when "culturally rewarded and practiced" is likely sufficient. The author is WAY too quick to reject the idea that PPEF executives could become this good at it just by believing that it's important. To me, this seems like something one could excel at with only a few weeks of practice and intent (note: I have no personal evidence of this, as I myself have not done so).
Separately "in software" is a ludicrously large category, with such a wide variety of cultural expectations as to be meaningless. There are places where appearance and poise matters a lot, and places where it might not be noticed on the third or fourth day you wore the same food-stained t-shirt.
I don't think it matters very much if you're (roughly) within the 'acceptable' window for whatever social environment it is in which you find yourself.
I tend to eat in a pretty messy way
Do you get food on your clothes or parts of your body other than your mouth (or immediately around it) or hands? Do you get food on the table/surface at which you're eating? Do you get food on other nearby people? If not, you're almost certainly fine, either "in software" or any other field. You might suffer tho in fields with a relatively larger proportion of upper or upper-middle class people, but you probably already know now whether you even want to enter the relevant 'tournaments' to earn an opportunity to enter those positions (and I'm guessing you don't). If you did tho, an etiquette class might be worthwhile.
But the author of the linked post clearly says that the “sandwich eating skill” worked against these executives. Their firm was passed over—and the strong suggestion is that their impeccable table manners were a not-insignificant part of the reason! The post is about the lack of importance of “sandwich eating skill”!
The post is about the lack of importance of “sandwich eating skill”!
Shouldn't this be phrased "the importance of 'lack of sandwich eating skill?'"
Sure, that too. It’s a set of complementary points:
I just read this post about the importance of sandwhich eating skill. The author describes how his investment firm served very hard to eat food to potential clients.
The author correctly points out that the executives must have been selected for sandwhich eating skill. Obviously it is bad to leave food on your face/teeth or have bad breath. I don't do those things but I tend to eat in a pretty messy way. How much is that going to hurt me if I stay in software? What if I move to other fields?