Why don't stud grids allow offset snapping?

[Roland Melkert]

Roland has always said that part snapping was meant to be geared towards making connections that aren't just as easily managed using grid snapping. 

Indeed, it started out as an assist to grid editing. Mainly because the whole snapping thing is kind of complicated  

Also the current version only matches a single snap point without keeping track of what's occupied so the closest best match wins.

For this reason I tend to limit the snap information to the most common connections to prevent many (many many) false positives.