Understood...from the perspective of a network, that strategy makes sense, IMO.
But...from the perspective of an individual user...I'd say that it has creedence but, again, the user is the biggest hurdle to a protected systems...and that goes far beyond whether he/she logs on as Admin or not. I'm not knowledgeable enough to say...but I bet that the folks in General Security will assert that logging on as Admin...is only a tiny bit of consideration that should be made...by any user interested in system security, safe computing, etc.
The fact that many users just do not take system security seriously...and are constantly looking for quick answers, tips, etc. that don't point the finger at them...would lead me not to overemphasize the importance or lack thereof...when it comes to logging on as Admin. Just my opinion.
If the OP wants a real answer to system security do's and don'ts...he needs to visit the General Security forum here at BC. I'll move this topic there .