YES they get worn out.. Im finally replacing mine after 20 years of loyal service..
Both Vertical & horizontal Zero lines are cut completely thru the mat up to like 20 or so... I cant read my 10,15,20,25,30 lines anymore and there are bias deep groove cuts that have become quite annoying when im cutting in that area.. So for $100 for a 20 year service that isnt so bad..
I have a sew/fit mat.. and I love it..