This topic has probably been beaten to death and I know I know "Git gud scrub" / QQ.
Now that this is out of the way. I'm not the best crucible player, but I'm also not bad either. The rumble grimoire is by far the hardest to get. I've come in 2nd more times than I care to admit. I've only come in first twice in TWO YEARS.
It would be nice if the first and second place finishers counted for grimoire or even better - if it worked like bounties do.
I agree - top 3 should count as a grimoire win. All other modes have a 50/50 chance of winning. It gives the game more push at the end trying to get into top 3.