That is true... Although i always point to one and the same article from PCPer, that surprisingly shows interesting results for even 860K...
The difference between 860K and i7 with 280GPU is 3 frames... 8350 and i3 - 5 frames, or less than 5% in Bioshock. 
Civ Beyond Earth has even less of a performance difference.
Metro Last Light actually performs better on 8350...
Shadow of mordor shows no difference what so ever...
Same with Sniper elite 3... No difference...
Some difference in Thief, but again 3-4 frames... Less than 5%...
In general: most games - no difference. Where there is a difference is in less than 5% ballpark.
I know 380 is slightly more powerful than 280, but it's still a reference.