Yes, fully agree with Fezzik. One of my strongest chess years was when I played in a lower division in my local chess league. I won all of my games, as I expected to, but many of them not easily. There is one thing being theoretically able to beat lower rated opponents but you need to practice actually doing this. 

I credit my subsequent higher standings in regular tournaments in large part due to lessons learned playing weaker opponents.

very well put

Obviously, if everyone tried to play only those higher, there would be no one to play. Everyone also can't only try to play those lower.

I wonder what the data says about what actually occurs on chess.com?

I agree; drug use in chess should be unacceptable.

That's funny...I wish I had intended it. 

I really should have more than one cup of coffee in the morning before I post.

I try to play mostly up,  but only slightly up.   I go for games at my rating level or higher,  which gives me a good mix of stronger and level players.

Mind you, this is just for online chess.  At club I'll play anyone whose free,  so the swing there is huge, from little kids that I spend more time demo'ing then playing, to the club masters who in turn spend more time demo'ing for me then playing.

It's always good to stretch yourself against stronger opponents, but if you're losing 80-90%, you're reaching too high. As Fezzick among others has said, you need to learn how to win! and this will only happen when you play a mixed level of opposition. It's instructive to try to hang in there with someone rated 400 points higher--at least until you make the inevitable blunder, but this won't teach you what you need to know. You need to learn to actually win a game from start to finish. so you need to play the bulk of your games against opponents who are somewhat beatable