Why do people put the TL;DR summary at the bottom? If the content is too long, and I didn't read it, then I'm not going to see a summary at the bottom. Abstracts, introductions, executive summaries, etc., go at the top. You don't even have to call it one of those: the goal of good writing is to engage people before they move onwards. I guess that locating it at the bottom is equivalent to adding a conclusion, and I'll grant that some people skim to the conclusion, rather than use the abstract/intro/exec-summary.
