Millions of rebuilds have been done without them and all the engines that have rolled out of Detroit since the beginning of time didn't either. But a torque plate can be a huge benefit. One way to look at it is if a block is not finished honed with a plate, when the head it torqued on every place a head bolt is close to the bore, the cylinders will have tight spots. So the rings will only contact the cylinder walls at those tight spots until sufficient wear occurs to wear those spots down to begin full contact so they can do their job properly.
I can definitely see the benefit of using torque plates. I contacted the machinist that is machining my block and head, and he said I don't need to use the torque plate. I agree with you, so many engines out there that were built without using the torque plates and they had no issues.
We rebuilt a 350 in '85 for my '56 Chevy 210. We mic'd everything, cut the ridges, used the ball-style hones for the bores, no align hone, no torque plates, reused everything except the bearings and rings, and after 194k miles on that rebuild I pulled the heads to have Pop do a valve job. It really didn't need one, I just asked him if it would be a good idea, and he said it wouldn't hurt, and to bring it in to the shop. No ridge in any cylinder. The engine never used oil or burned oil, never overheated, and ran like a top. After Pop finished the heads it had much better throttle response, and still didn't use or burn oil. I thought he ported and gasket-matched the heads, he did not.
So I will be moving forward without using a torque plate on my 292. I trust my machinist and his expertise, as he does excellent work.
