My definition of "bottleneck" in pc terms is a component which keeps any other improvement from being effective.
I think it is much overused.
I would prefer to call such components as limiting factors.
There will always be some limiting factor.
The difference is in the Intel architecture which does more work per clock.
One thing which the OP got right is the balance in budget between the cpu and the graphics card. The graphics card should be budgeted at about 2x the cpu for a balanced gamer.
Talking about graphics cards, the R9 cards are currently overpriced because of demand by the bitcoin miners.
A R9-280X is in the $400-$500 range.
A comparably performing GTX770 will be in the $350 range.
As to intel vs. amd for gaming cpu's, it largely depends on how many threads your game can effectively use.
Just because you see activity in the task manager across all threads, it does not mean that you are multithreaded. You are seeing windows spreading the activity around.
In fact few games can use more than 2 possibly 3 threads.
Look at this older report on <$200 gaming cpu's:
http://www.tomshardware.com/reviews/gaming-processor-frame-rate-performance,3427-9.html
You will see that the i3-2120 was comparable to a FX-8350.
The 8320 in question is a bit slower and is a $160 chip.
By comparison the i3-3220 in the report is slower than a i3-4130 @$125.