As AronTimes pointed out, they aren't necessarily capable of matching modern ones, but besides, it wouldn't be that incredible if they could.

The shape and means of operation cannot be changed without making it "not a violin", so only the build process and quality can be improved. The build process has been improved significantly, resulting in significantly lower prices and higher availability. From the build process perspective, modern violins are obvious winners without peer: vastly more musicians buy modern violins rather than Stradivarius models. I reckon if the musicians would have been asked which violin they would most like to purchase, the number preferring the new instrument would have been quite a bit higher than just 62%.

For build quality, the "good enough" stage was reached before Stradivarius. The "great" stage was reached by Stradivarius. We could do better nowadays, but there's no point. We could construct violins with <1µm tolerance on parts and placement. We could make them out of materials with less variation due to ambient temperature and moisture. We could 'improve' a whole bunch through our 300 years of manufacturing advancement. But the music wouldn't come out better with such a violin. Any imperfections left in a Stradivarius violin are expected – required even – for the typical sound of a violin. Removing them would make a worse violin.

In fact, we have more precise/perfect musical instruments nowadays. They sell for a couple (tens of) thousand bucks a piece.