Uplay is a DRM relic which was created because the publisher did not understand how piracy worked and why it happened. The success of Steam showed that the best way to tackle piracy is to create an online environment for the players - multiplayer, mods, community, achievements - there by indirectly restricting content for pirates and creating an incentive for them to purchase the game, even after they played the hacked version.
Why Uplay still exists right now is beyond me, maybe they plan to turn it into something similar to Steam/Origin in the long term.
Why Uplay still exists right now is beyond me, maybe they plan to turn it into something similar to Steam/Origin in the long term.