That's what I was trying to say, but you said it in a much clearer way. Thanks!There could be instances where the correlation doesn't apply. If you brew a low gravity beer with a yeast that tollerates high alcohol content, you won't get to the point where the alcohol will affect the attenuation. And if you brew a high alcohol beer with a yeast that easily handles the alcohol it will also not affect the attenuation.
Thanks for the great response one more question is attenuation only refering to fermentable sugar or all sugarAbsolutely. The higher the ABV, the less efficient and healthy the yeast are. Pretty much every yeast strains will have a given alcohol tolerance (expressed in percentage) under "typical" wort conditions and acceptable pitch rate. Once this tolerance is exceeded, you'll start to see stalled fermentation and higher FGs.
For example (using generalities and typicalities here), Wyeast claims their 1056 strain has an attenuation of 73-77% (let's assign 75%) and an alcohol tolerance of 11%. If you brew something big and use 1056, if your beer has the potential to go beyond 11%, once you reach that 11%, you could only get 70% attenuation and stall in your fermentation.
Here's a good position.