No, the purpose is to stop conversion. When you fly sparge, especially on large systems, it can tale 12-3 hours for the sparge. All that time you're in conversion range, and increasing the fermentability of the wort. A mashout fixes the fermentability at whatever level you like. But you need to hold the mashout temp for at least 20 min. to do that. Many of us (me, for one) sparge at hot temps to make sure conversion is complete, but we don't go high enough or long enough for it to truly be a mashout. Some people have the mistaken idea that a hotter sparge reduces the viscosity of the sugar and gets more out. But we haven't reached the limit of sugar solubility at mash temps unless your gravity is over 1.300. In that case, hotter water would help.