Many small boats, such as my Lido 14 and others do use bolt ropes on the main. Among my sails is an old set on which the rope luff has indeed shrunk. I can get rid of most of the problem simply by really applying a lot of force to the main halyard when hoisting. The main halyard should be rod tight even on a small boat like that. You are not going to hurt anything by trying, and if it doesn't work, take the advice already given you. A sailmaker can put in a new rope luff quickly and inexpensively.