I think former D1's point is being missed. If you have run hard enough and well enough to train alongside elites before they became truly elite, then you know there is a vast gulf between achievement levels. Former D1 knows he would never claim to be elite out of respect for the dedication and talent he did not have.
The derisive term hobby jogger applies to those who conflate casually lacing up their shoes and huffing and puffing through a few jogs a week and the occasional 20 min 5k (or slower depending on age/gender) into an impressive achievement on par with say someone cranking out 80+ Mile weeks, sacrificing evenings out with friends all for the chance to push their body past its limits during workouts and races that are unfathomable to the average jogger.
So the as to why the derision? That comes in when the hobby runner gets enough of hearing the hobby jogger trying to insist that joggers and runners are the same because they both ran the local 10k that morning despite one running balls out and finishing 2nd in 31:14 and the other sweating along to his iPod for 45 or 50 minutes, essentially devaluing all the extensive effort the runner is putting in to achieve personal gains. This is kind of like an actor telling a circuit court judge we are the same because the actor once played a lawyer on TV.
TL;DR: hobby joggers are the holiday inn express of weekend athletes. Everyone is glad you are improving your fitness, just don't insult my hard work by exaggerating your efforts.