I had raised beds when I lived in Virginia, & they gave me the best crop of lettuce I ever had! My only problem came after about 3 or 4 years, when the plum tree roots worked their way into the soil. Couldn't get rid of those darn things.
I'm in upstate New York now, and put in a couple simple beds last year. (Our "soil" here is just rocks that the glaciers left behind, with a little token soil thrown in to tease us, so tilling was way too much work).
All I did was lay down cardboard and newspaper on the ground, then top it with compostable kitchen scraps, a shovel of "soil" & some grass clippings every so often. Eventually, when the beds got about 8" tall, I capped them with an inch of top soil/peat moss/sand mixture. Then I planted pepper and tomato seedlings right into the pile. No rototilling, no turning the pile, just plopped 'em right in. They did super! We had enough to eat, and froze about 40 quart bags of peppers to boot.
Not long ago I was reading about a German way of making raised beds that sounded even better. They call them "Huegelbeete". They're about 4 feet tall and quonset-hut shaped.
The layers start with branches at the very bottom, then they build up the bed with manure, leaves, grass and so on. The ideas are:
(1) the bed takes about 6 or 7 years to break down, so you get a lot of "mileage" from your initial work; (2) it's high enough so that older people or people in wheelchairs can still garden, because they don't have to bend over; and (3) it's super efficient, because the quonset-hut shape gives you more actual square footage to plant--that is, you're planting up both sides of the "hut" and on the top, not just in a rectangular shape like you do when you plant flat on the ground.
I don't have any trees around, so no branches to try this out, but the technique sounds pretty cool. It reminds me a little bit of the old "hot beds" from years back, when fresh manure would be used to heat up the soil so you could garden in the cold months.
Maybe that Master Gardener needs to rethink things a bit!