I am not agreeing or disagreeing but to be a true expert you have to niche down and spend so much time in a small area of expertise that your broad base knowledge usually suffers. Conversely, to appeal to a large audience you need to have a wide and consequently more shallow expertise in each area. 3 million+ subscribers says to me he is doing the latter and probably doing a good job at that and making a good income for himself. So good for him.
I bet there are top overlockers that don't know crap about networking and great network engineers that have never built a computer themselves. There are great surgeons who you would not want to be your child's pediatrician and vice versus.
So he isn't an imposter and maybe he is a good expert for the masses. He appears to have more expertise in a wide range of computer-related areas than average so, he is a good person to provide news and advice to the average person who wants to do something occasionally techie. Obviously, if you are on STH forums discussing, something like how you are going to do 40 gig networking on your home NAS/SAN then, you are going to see that his networking knowledge and other areas are beneath yours.
IMHO if you are going to criticize him, it should focus on whether he is good at teaching/explaining or not and whether he is oversimplifying to the point of doing a disservice or failing to refer viewers to niche experts when they will need it. I do not know enough about him to have any comments on those topics.