The point is just to quickly
check Radius connectivity to help you diagnose a problem. As someone points out earlier in thread:
-user calling "hey i can't login"
-technician; ok, let me see. <performs radius test>. ah, i see the problem, working on it.
diagnose in 20 seconds, simple an plain, without searching in logs, which can be long in some cases
monitoring radius response time seen from the mikrotik client (can't have this in logs)
Mikrotik device already does that, when you create your radius client, it sends some kind of ping automatically. We're just asking for a command to do that test when we need (/radius check)