Almost all commercially produced fruit, including but not limited to grapes, blueberries, apples and cherries, are grown using cuttings and never from seeds, most of the most popular fruit varieties are sterile whether or not they still have a seed/stone/pit in them. I don't see that there is any difference in this with avocados than with anything else.
I also don't really see the need for pitless avocados as surely there aren't that many injuries and those that do occur can hardly be life threatening. What WOULD have made sense to me was to breed a variety with a very small stone, so that you could be sure of having more flesh on each fruit.