No it doesn't, generally speaking means NOTHING.
The two topics are not related and should not be used for "Rough calculations." Nonsense like that is why folks over-rate their power supplies.
EDIT: The efficiency of the PSU does nothing to change how much power a component will draw.
ok lets suppose we put the theory to the test.
IF someone wanted a PSU recommendation for a triple SLi GTX780 with a 4770k what do you feel is a good wattage to recommend assuming we are recommending PSU's listed in this thread?
using the TDP rough guess method, I would personally recommend a 3x250w(TDP for 780) + 84w(TDP for 4770k) + 100w overhead for other components such as fans, HDD, RAM, etc.... this comes out to a total of 750+84+100 = 934w and since there is no PSU of that wattage, you go to the closest one up which is a 1kw PSU. do you feel that a kilowatt PSU is an overestimation for a 4770k with triple SLi 780's? taking into consideration of modest OCing (nothing crazy) and gaming and some benching loads? granted that system would not likely pull more then 800w from the wall, but the power band that you are hitting is within safety buffer you want to have anyway. after all, we don't want to run our PSU's at full blast since high utilization also means really loud PSU fan acoustics. (not that it matters when running triple SLi )
i've said it many times over. it's a rough estimation. more of a general rule of thumb method of looking at things and get a quick answer. it's not scientifically accurate, but it's close enough for most situations.