What I'm saying is that in comparing gnomes and halflings, we're willing to blindly accept one lazy hacky workaround (vaguely described illusion proficiency), but not another (natural stealthiness, luck, and insularity)...and there is no good reason that the former is better than the latter.
They have equivalent amounts of logical support. There is no larger leap here.
It's D&D.
The only things widely accepted as an excuse for anything are
- Magic spells
- Magic items
- Money