I would think the answer to this is (as it is too often) "It depends".
Our manuals refer to "wind", but do not say which one is to be considered. Is it the FMS/IRS calculated wind with its known lag and general inaccuracy, or is it the ATC report that only is averaged over 2 minutes? Both of them are inaccurate and only give a rough idea of what one might find when landing and taking off. On top of this, ATC at certain fields have been known to "tweak" the reported wind to suit the supposed needs of traffic - I have been told of calm wind and dry runway by ATC in a torrential downpour and more than 10 knots of tailwind already.
So with the ATC reported wind within the required envelope, if the landing at hand is close to performance limits, one will easily be way more G/A minded in case of an arising oddity like FMS showing an out of limitations tailwind than when landing on a non-limiting, long runway without terrain around and with a low landing mass.
Performance-wise, there is a little safety margin in the calculation, if I remember correctly: a tailwind is triply and a headwind is half considered in the runway analysis tables. While this is of course in no way an excuse for a sloppy performance calculation, it will usually cover for some minor wind fluctuations between the time the calculation is performed and the actual takeoff/landing.