There's so much about #DnD #DnD5E that can be simplified or genericized. The initiative system bogs down gameplay, for one.

The class-based character development system and magic system are both way too complicated for new players; those are actually my two most hated aspects of the game, and I've been complaining about them since the late 1980s. I started playing in 1981.

The reason for this is that #DnD5E has as one of its core mechanics that idea of advantage or disadvantage, where you roll twice and take either the higher roll (advantage) or the lower roll (disadvantage). Having two dice of each type makes this easier, and having them in two colors can make distinguishing them easier.

In the case of d6, the most common method of generating character ability scores is rolling 4d6, and dropping the lowest die, so having four d6 to roll at once is nice.