He's wrong.
Proc amps are a type of processing, and all processing can be good or bad. Most have both some negatives and some positives, and getting needed results can be an art.
You can't always correct color in software. When you're doing things in software, your using RGB. But a proc amp is in the native analog YUV. It's not the same concept when you color correct.
All proc amps behave differently as well. Yes, sometimes that BVP4+ is not ideal. and causes more harm than good. Other times it will help better than anything you can do in software, and looks better than the uncorrected signal. Let your eyes guide you. Not dogma. When it comes to color correction, you'll notice I've never been dogmatic. It's art, not science.
My favorite proc amp is usually the built-in on the TBC-3000. But a BVP4+ is still in my toolbox. As is Adobe Premiere,
VirtualDub ColorMill, and others.The more tools you have, and learn to use them, the better you'll be.