That statement is just wrong. While you typically do have to have a decent class rank (top 1/3 to 40%) you definitely don't
need to be in the top 20% to land ortho. Heck, we have a current 4th year who is in the
bottom quarter of the class and matched ortho at a decent program. From what I've gathered, MD prefers you to have a higher class rank and solid boards. For DO, class rank doesn't matter nearly as much but you've got to get strong boards.
However, the thing both types of programs want are people that are a) going to be a solid fit with the rest of the team and b) going to be willing to come in at 6 am and stay until 7 or 8 every day and almost constantly be on call. Ortho programs want to see commitment. Period. They need decent boards and class rank to know you're competent, but the LORs from preceptors saying you're the first one in and last one out and are always willing to do the work are the things that really impress the programs. Or so I've been told by our deans and 95% of the 12+ orthos I've shadowed.
That's a bit of an exaggeration. The residency programs I've looked at give you between 12 and 20 vacation days/year and people can definitely take holidays off. The hospital/clinic still needs to be staffed on holidays though, so not everyone can get every holiday off. You also don't have to be in there every single weekend. The few residents I talked to said they rotate, so they work one weekend then take call for 2 weekends. Some weekends they didn't have to go in at all, some weekends call sucked. That's true for anyone on call though. It is a rough lifestyle for residency compared to a lot of other fields though. Especially ones like PM&R or Psych where 50 hour work weeks with minimal call aren't uncommon.
@cliquesh already got this one, but to add another stat, ~245 was the average step 1 score for MD students that matched ortho in 2014. That means half of them were below 245. You don't need all those things to match ortho, but they certainly help. You'll always need solid letters and evidence that you're gung-ho about ortho (willing to work your ass off as previously stated), however the other stuff is much more variable. If you kill boards and class rank (i.e. top 10% with 260) then the other stuff like research, ECs, etc. becomes less necessary. If you're in that more average range (top 35ish% with a 245ish step 1), then you'll need the research, pubs, relevant ECs, etc. to help give your app the boost to land an interview.
Everyone on SDN seems to think that things are much more cut and dry than they really are. You don't have to hit some specific magical board score or class rank to get into programs (usually), but you do have to provide an application that proves you are a strong candidate for that program.