"is this really a real problem?"
Yes absolutely. Even the most trivial web application has to confront issues surrounding concurrency. Servlets are accessed by multiple threads, for example.
The other issue is that threading and concurrency is very hard to handle correctly. It is almost too hard. That is why we are seeing trends emerge like transactional memory, and languages like Clojure that hopefully make concurrency easier to deal with. But we have a ways to go before these become main stream. Thus we have to do the best with what we have. Reading JCiP is a very good start.
