I believe that one [of the many] factors which separate an enthusiast, a hobbyist, an amateur and a professional is the expectation of performance. For example, the expectation for professionals is to perform at a high rate of skill for a greater period of time. To claim a professional set of expectations (to perform at a high skill level for an extended period of time) for most in aikido would not be a true claim.
Why is it relevant? I have a job. Aikido isn't it. Therefore, I am not a professional. Only a tiny minority of aikido practitioners could be said to be professionals, so why is that a relevant standard?