I think the whole problem with the term 'bottleneck' is the fact it's a one word answer to what could be a host of different problems. Each case is different, surely. Cpu intensive games will obviously suffer with lower end cpus regardless of your gpu, where as lighter usage cpu games that love to pull on the gpu specs will suffer less if your gpu is up to it.
A one word term can be quite misleading for something that is bespoke dependant on what the use is for, no?