I disagree, plowing still has its place today, just in a more limited role due to a lot of reasons.
As with everything, microclimate and soil has a lot to do with it. Where I live, our soil has a lot of manganese so it is prone to compaction, so tillage really matters. I just got done plowing up a 10 acre field, in part for that reason, but also because I am in the midst of crop-rotating it from corn into grass ground. Deep plowing it with a overturning plow really allows me to get some nutrients and organic matter down into the soil where it will do good. How good? On an 8 year rotational schedule soil tests reveal I am actually getting on the high side of organic matter; and yes you can have too much. You want
water to move through the soil not getting all clogged up. A reliance on solid cow manure on corn ground has aided that rather then pelleted or liquid urea too however, but how are you going to get the most use of that NPK (especially nitrogen) without immediately incorporating and capturing it without tillage?
In this case I had no other options, I had to get the corn stubble turned over, but in recent years vertical tillage has made strides as science and mechanical engineering has really dovetailed well. It uses less horsepower and fuel to do as well.
One side note about small animal power though while plowing is that it is not the sheer power of the animal, but the speed. In order to effectively plow, you must go as quickly as you can (within reason); one of the few tasks on the farm where going as fast as you can, makes for a better job. Considering the strain it takes to pull a plow through soil...at a pretty good clip...takes strength AND stamina.