It is an additional way to qualify

The normal Sneak Attack methods still work. Rakish Audacity simply adds another qualifying situation.

The spacing condition is about creatures around you

The feature rewards isolation and dueling. Crowded melee can disable this special route, though normal ally-based Sneak Attack may then become available instead.

Disadvantage still blocks it

Rakish Audacity does not override the base Rogue rule that prevents Sneak Attack when the attack has disadvantage.

Fancy Footwork supports the duel

After making a melee attack, you can usually step away from that creature without provoking from it. This makes it easier to choose a new duel or protect yourself between turns.

Charisma has real mechanical value

Adding Charisma to initiative and using Panache later means a Swashbuckler gains more from Charisma than most Rogue archetypes.