OK, since it's odd that no one has responded yet, I'll try to write more objectively and intelligently:
This isn't about mashing, but rather about post-mash additions. As Gordon Strong suggested in his new book, roasted grains add bitterness when mashed, and as an alternative can be added at mashout (as can crystal grains). Also, the steeped extract of roasted grains can be added near the end of the boil, or in fermentation.
Many do not do a mashout, but the principle still applies IMO, that if you steep malted grains after the enzymes have been denatured your OG will rise correspondingly, but so will your FG. Even if batch sparging, if you drain, then add hot sparge water, let it sit awhile, add grain, let it steep, a similar result happens.
I can see where this might come in handy, like if time got away from you on your mash schedule, and you knew that it was going to attenuate too much, you could raise the grain bed temperature to mashout levels, let it sit to denature, add some grain (even base grain), let it steep, and get some body back into the wort.
Anyway, before trying it I had not considered all this, and to me it's kind of interesting. Cheers