I'm not sure how many climbers are motivated by grades, but I certainly know some climbers whose climbing is all about grades. While I can completely appreciate the desire to improve at climbing - or whatever endeavour you are pursuing - I find the obsessive compulsion to climb at a certain grade detrimental to improving performance.
These are the people who thrash and flail their way up a route, of whatever grade, declare it climbed, and then move on to the next thrutch-fest. Apart from ingraining poor control, footwork, body positioning, etc., it's not clear to me how this improves your climbing. I guess, you could, at a stretch, say "Oh yeah, I climbed 'Triple X Route, rated 13c' - or whatever", but, did you really?
One of the benefits of climbing as poorly as I do, is that you just don't care about grades. 5.4, 5.7, 5.10, it's all the same to me. Either I enjoy climbing the route because it feels easy, or I enjoy climbing the route because I had to work at it. I'll work hard to complete a route, but, I won't endlessly thrash on one that is clearly too hard for me. Climbing out of control, as one does when thrashing, is not something I want programmed into my schema of movement. I'd much rather lower off and let someone else have a go.
Having Fun at Prophesy Wall in St. George, Utah