Replying to Breaking in liners vs getting them molded

So I just got a pair of k2 method pros. At first the liners were super tight and pretty uncomfortable but after a day of skiing the liners have broken in a good amount and conformed to me feet somewhat. Originally I planned on getting the liners molded to my feet but after today I really don’t understand what the difference between getting my boots molded and just allowing them to break in over time is. This is probably a kinda dumb question