Teams have to acquire their franchise talent via the draft, unless they happen to be a leading destination for superstar free agents. In particular, the most difficult spots on the roster to fill are: a) dominant big man, b) dominant PG, and c) dominant, creative wing scorer. No other team in the league is going to trade you one of those three core players that create mismatches unless they are under duress (e.g., player makes a trade demand, player is going to leave in free agency, etc.).
If a team can draft a dominant big man, a dominant PG, and a creative wing scorer, the other pieces--such as, wing defensive specialist, perimeter shooter, interior defender/rebounder--can be acquired thereafter. A team that is becoming a solid contender also becomes a more attractive destination for free agents or other players acquired later in the draft, assuming the team hasn't wrecked its cap space with bad contracts to mediocre players.
The draft may not yield franchise-level talent, but for a small-market team, there's no other way to get it.