The experience of free will can be real, without free will being real. An individual believing it has free will, will certainly act different to an individual that believes all actions are predetermined. I think what your parent commenter meant was that society might be better off if the notion of free will was not taken for granted by its individuals, hoping this would inspire compassion and tolerance. Of course, if free will isn't real, this isn't something anyone would be able to influence. It would still be possible to come to that conclusion deterministically.
Looking at this from the angle of social organisation, I think without the notion of personal responsibility, we lose more good things than we would gain by assuming life is deterministic, and I don't see how we can keep personal responsibility when giving up on free will. There is a consideration of trusting other people to be cooperative if they stand nothing to lose by being selfish to the detriment of others hidden somewhere in there too.
Looking at this from the angle of social organisation, I think without the notion of personal responsibility, we lose more good things than we would gain by assuming life is deterministic, and I don't see how we can keep personal responsibility when giving up on free will. There is a consideration of trusting other people to be cooperative if they stand nothing to lose by being selfish to the detriment of others hidden somewhere in there too.