According to the leakster, the reason behind it is because the development team decided that they’d rather focus on the story and single-player gameplay, which saw them put multiplayer aside in favor of that. However as Game Rant notes, while some of the previous titles did feature multiplayer, the previous release did not so it shouldn’t really be that big of a deal.
Besides, Assassin’s Creed is a game that focuses more on the story and gameplay rather than battling it out with other players, so we reckon it shouldn’t be that big of a loss. Besides with one less mode to focus on, hopefully the development team will get it right this time. That being said, despite the game lacking multiplayer, players can still expect things like microtransactions.
Exactly what will these microtransactions be used for remains to be seen. We’ve recently seen screenshots of the upcoming game leaked and in a recent press release, Ubisoft has confirmed that there will be a new Assassin’s Creed coming in 2017-2018 (along with Far Cry), but exactly what we can expect is still unclear.