I have not had that particular problem with my smartwool sox. (I have had that problem with a leading chain of socks and no longer buy my sox there)
the socks I am wearing today are on their 3rd season now and i wear them all year round. (taking off shoe to examine sock)
the bottom of the toe and heel areas are noticeably thinner but all stitches are completely intact.
maybe it's your shoes (I have no idea)
my biggest problem is some kinds of "smart" wool are not so smart; and they shrink. These however, did not