I agree with a lot of what he's saying, but at the same time, why does it matter? Does every book need to be easily enjoyable as light reading by anyone who is literate? Joyce was highly educated and exceedingly well-read, and he wrote (in his later works especially) for an audience similar to himself on those points. The only downside is it limits his potential audience, similar to how a writer of obscure fanfiction or someone who blogs about niche subjects limits their own potential audience. His particular niche was writing for literature nerds.