NFL Wild Card - Offenses are usually better when they can do more things. That's a simple way to look at it, but if offenses are supposed to be the ones dictating the matchup to defenses, it is easier for them to do that when they have more tools available to them. Uncertainty breeds hesitation from the defense.
The Bills did not have the benefit of that kind of variability on offense for most of the year. Josh Allen being a cyborg with a crew of good pass-catchers was more than enough to put together an effective offense anyway, but it was clear that a portion of the team's volatility could be chalked up to an uninspired run game.