According to this posted answer, a MacBook Pro will throttle because otherwise its power consumption might exceed the amount supplied by the AC adapter.
However, from my experience, my 2012 MacBook Pro has never gone over perhaps 50W of energy usage, as shown with iStat Menus. My power adapter is an 85W MagSafe adaptor. Because of this, it seems like even without throttling the power consumption never would exceed the amount used.
So why would this MacBook throttle if I took out the battery, as suggested by the answer above, even though the power adapter can supply enough power to sustain peak performance?