True. But generally scrappers have enough survivability they don't ever die. So you have to weigh this in also. Storm Kick is the highest DPA in the set.
So lets say we have a MA/NIN scrapper with the +Big Crit chance ATO in Eagles claw, which also provides a crit bonus. You could go Eagle's Claw from ninja hide, to Storm Kick. You would have a very high crit chance on both attacks. Then follow up with some other attacks till Eagle's Claw is up again and repeat.
Maybe not Stalker level of crits, but about as close as a scrapper will come. And since Stalker MA is ST only, a pretty good alternative. Plus Scrapper NIN is a good set, that you can softcap easily no need for the 7.5% there.