I would have thought they would not get sharp if on appropriate groundI have played in walking trainers, astro trainers and football boots. I preferred the boots/astro depending on ground condition.
However I have been told that I can not use my boots unless I get the studs changed as metal tips are not aloud. Something about they may become sharpe.
If on hard ground, gravel, Tarmac etc then there will be wear. In such case it's not appropriate for metal studs
If it's grass etc then they won't be worn away - but they may not want you ripping their turf