Right, I didn't explain myself.
Dextrins are especially nice in beers with lots of roasted grains. They soften and balance out the astringency.
Grainbill, mash temp, adjuncts (esp. maltodextrin), gravity, and fermentation are variables to adjust to set dextrin levels in beer. Single infusion mashes can take place anywhere from 147-160°F, so when you want to turn that variable up, it's perfectly acceptable to set it to 9/10ths.
The Porter I just brewed, from an AHS recipe, has the mash temp, fermentation, and adjunct dials turned all the way up to compensate for the low gravity and grainbill settings. For balance.