In a nutshell, lack of knowledge of the opening game isn't really why he lost, but my point is that it adds to things when you play poor openings and also have poor ideas. It would help, if he spent some time abandoning his d4 campaign and start playing e4, but oh well. You can play whatever you feel like, just don't get mad at me when you find that you have to memorize more lines than you wish you had to in the beginning when you should be focusing more on tactics.
I agree with. you. But it's not opening learning deep variations of particular openings. It's just about understanding opening principles. 2. Be3 is clearly not a very good move if one understands opening principles.