Oh yea absolutely, I'm not suggesting the leaderboards themselves are broken, it's the method of collecting points (or counting moves as it were, etc.) which is a game design issue. I'd love to think that if a developer realized such an exploit existed before release, and that fixing it would be too difficult or time consuming a task, they would just remove leaderboards from the game altogether. But, they don't, because it's a bullet point that's pretty much expected in modern games. I'd guess that most exploits are found after release though. QA never finds everything.
I'll stop ranting about it in a sec, this personal gripe probably doesn't bother many other people. For me though, sometimes it discourages me from playing a game. Especially in LBP's case where the "Next Highest Score" displayed prominently in the upper left corner of the screen, and was more often than not a legitimately unachievable number. Or in IloMilo's case, where for a few days I was relying on the end-level screen to tell me what the "correct" solution to a level is since I thought it was a good assumption that the best community score would be the fewest steps possible to complete a level, then I would try to duplicate that number. It was a fun meta-game. Now, the best community score is always 1, ruining that part of the experience for me.
I'm probably better off not letting this stuff get under my skin because it seems like a problem that can't be addressed wholesale or is just not worth addressing.