While this is technically true, it really offers no benefit to ski them on their own. Liners will last about 150 days of skiing. If you want the most out of your liners, sure you can ski them without molding and grunt it out for 10 days until they fit but you ski the first 10 days in less-than-ideal comfort. If you get them properly molded in the shop, it slightly reduces the life of the liner by about 10 days but you will have 140 great ski days left. It's not really worth it to not get them molded.
If you let them mold on their own, you will not get as nice of a fit compared to someone properly molding them to your foot and also the shell. Having the proper duration, tempurature, toe cap, toe elevation, etc really makes a difference in how the liners fit and feel.
Like I said in an earlier post, you purchased these liners for the point of getting a better fit. If you don't heat mold the liners, then the boots are not living up to their potential and you are not getting the most out of your money.