No, it's not even that--it needs to both be beneficial to society and be produced at the maximum possible productivity. (In Capital, Marx uses an example of automatic looms to make this point.)

Once automatic looms come out and double productivity, according to Marx, all the hand-loom users get their pay docked to 50% of the original.

Isn't that the loveliest incentive for technological advancement? If I were a hand-loom user, I'd riot against any company working on automatic looms.

People are lazy, but they also coordinate with each other. Why make anything better when you can do the minimum and all pat each other on the back?

The whole scheme just doesn't work--and for other reasons, too. Suppose I have some really fertile land and I can grow strawberries really easily. You have less fertile land and it takes you twice the labor (the plants are half as productive, let's say, but the same amount of work to care for). But because it's based on labor, not output, why would you bother looking for better land? Who cares? Inefficiency is baked in, to whatever degree laziness allows. Or, alternatively, if your work now isn't considered to be fully "socially necessary", in what sense are you not just paying for output?