Easily. I experienced severe needle jet wear in a Ducati with the stock 38 mm Mikuni flatslide downdraft CV carbs, after approx. 40 000 km/25 000 miles, although I installed Dynojet needles somewhere around 20 000 km (some said that Dynojet needles were harder on the jets than oem Mikuni needles)
When looking through my worn needle jets, the orifice was sort of "pear shaped" (fitting description, eh?)
IIRC, my fuel consumption increased at least 20% with the worn jets, before I changed them.
So an old XS 11 can definitely suffer from that problem. And it is much more likely that the jet is worn, than the needle.