I had a short competition "career" many years ago (competing with Rick Jones and against Henry Joe Peterson....both TVWBB members who have not been seen here in a LONG time), and I think that what Rod says is very true. You are cooking BBQ to please a trained BBQ judge (hopefully, though this isn't always the case.....), and the things that trained BBQ judges are looking for tend to be a bit specific, but will also vary regionally. The most challenging thing about comp cooking is figuring out what "perfection" is for the general judging community, and then getting all of that into ONE bite (for taste and tenderness), and a somewhat short look at your prepared box (appearance.) Let me tell you, I've eaten a lot of winning ribs (as a competitor, judge, etc), and in almost every case I would not want to eat a whole rib prepared that way. Good for a bite or two, but not much more (for me, at least.) And many of these competitors are cooking HUGE amounts of meat (3+ shoulders, 3+ briskets, 6+ rib racks, etc) to get the best bits to turn in, so there's that part of comp BBQ that doesn't appeal to me either.
In the backyard, you are cooking what YOU like, or what YOUR family likes, or what YOUR friends like. For some that's falling off the bone, for others it's something else. For some that's heavily seasoned, for others it's light seasoning/smoke so the meat shines. In your backyard, there are no parameters you feel like you have to hit to please a judge in a single bite, and, for most of us, even the cooks that we think didn't turn out as we'd like will still likely impress family and friends, which, as Rod says, is what you want to do as a host anyway.
Competing was fun, I enjoyed the challenge of it. I don't think it relates much to backyard, except in the case that I did get much better at controlling variables (seasoning, smoke, heat, etc.), which are skills that come in handy.....especially when something is not going as expected.
Just my thoughts (while I reheat some backyard bbq for lunch.)
R