if I write a web crawler and send off requests to 100 web servers, then handle results as they come in, those 100 web servers are working in parallel to get me my data back. So while I can't process the IO in parallel I am parallelizing my workload. Without parallelism of some form, your program would take the entire time the non-concurrent form takes.
Those web servers are working concurrently; they may or may not be working in parallel, that's an implementation detail. Without examining the wait states on the processes, you can't easily say.
The two terms mean something technically different. The article isn't about parallelism.
