OME will also tell you the 891s can comfortably handle over 200lbs of extra gear, but anybody using them with an plate bumper will gladly say otherwise.
Also this is probably the first time I've seen anybody say the 881s are for additional weight. Everybody that offers them will advise they're for stock weight. That'd be the 883s instead, which they didn't even bother listing, to boot. Not to mention 890s are taller than 891s, both of which offer more than 2in.
The problem with that chart is it's trying to include ALL the 3rd gens, and they weren't all made equal. For example, Highlanders were 1in taller than every other 3rd gen offered.