Earlier quoted context omitted.
People definitely stop reading after the first answer, especially if it looks like a reasonable solution. It is a very common experience for me, where I won't realise that there is a much better rated answer below the accepted one, especially if the top answer is long enough so that the second one isn't visible without scrolling. From a UX perspective, you want to put the most relevant information at the top. The vot…
There's zero evidence that people stop reading at the first answer. Otherwise no other answers would have any upvotes, and you can see that's not the case.
Also, I'm sure the claim isn't that everybody stops reading after the first answer, but that the first answer does get a lot more reads than answers further down. I bet it would be possible to prove this with the right analytics.