Yes it can affect the playability. When the frets start to get grooves worn in them... it obviously creates a low spot on the fret wire. This can start to cause fret buzz due to the fact that a certain fret may be worn more than others... It may also make a certain fret harder to hit clean notes quickly on... due to the low spots on the frets... but that's not much of a probably unless you use vintage sized fret wire like I do. Most people now days use Jumbo... or medium jumbo fret wire to make it easier to fret notes. Wear doesn't affect bigger wire as much as it does vintage sized/small fret wire. If it gets to where you start to hear buzz... You can always take it in and have a tech resurface the fret wire... this will even out any low spots.