The statement is not "silly" and is a decent first approximation to understanding tasking and threading.
A task/thread has a set of registers, a memory address space (populated with RAM and sometimes ROM), and the ability to execute instructions. This is the same as a basic CPU. So one can conceive of a multi-tasking or multi-threading system as being a collection of CPUs.
(And, to carry this analogy further, there are situations where multiple threads/tasks are simulated on a single thread/task.)
Yes, modern CPUs have a lot of extra registers and controls for, eg, controlling tasks and threads, but that's going beyond the basics.
And, from the standpoint of multi-threading within an OS, it is true that there are essentially the same concerns about synchronization and atomicity whether you have multiple streams of execution running in multiple threads on a single CPU, or the multiple streams each running on its own CPU. The only major difference is with regard to cache coherence, and even for that case there exist systems where each thread on a single CPU has its own cache.
