In tabletop D&D advantage isn't something you can easily get by yourself. Instead, you have lots of spells/abilities/maneuvers that grant advantage to your allies. It was designed that way to increase social pleasure around the gaming table. If the party fighter downs the monster because my spell gave him advantage on his roll, we both get enjoyment from that moment. Also the D&D rules system was designed around the idea that advantage should be rare and you need to use up some resources to get it, so it feels meaningful every time.
It does not makes sense in a DnD video game that set out to adapt table-top rules to a PC game. There's literally nothing about the base mechanics of 5th edition, that are geared towards "social pleasure" rather than efficient and balanced combat resolution.
