The message that I'm taking home from your post is that if we wish to be "less wrong" we should avoid sarcasm. Here is my analysis.

The first paragraph alludes to the fattening of America in the recent past. Something has changed. The article about exercise talks about different genotypes responding differently to exercise, but it is not offering a diachronic account of the recent fattening. It seems unlikely that gene frequencies in the population have changed, leaving more people immune to exercise today than in the recent past, and the article does not propose this.

So hidden beneath the sarcasm is a relevant point, that immunity to exercise hasn't undergone a recent big change. How much damage has this done to the logical coherence of the post?

Paragraph 2 talks of self-handicapping and making excuses. That sounds like human nature to me, and human nature hasn't changed in forty years. So the same knock-down applies to both immunity to exercise and to self-handicapping.

Now AlexU may wish to come back and say: the rise of therapy culture and psycho-babble are big, recent changes. I'll leaving those who favour this view to argue for it.

What I'm noticing is that the implicit negation in sarcasm makes it harder to follow the internal logic of a post. Using sarcasm makes it harder to write a clever and internally consistent post.