Dollar-cost averaging is a schedule, not an edge. It does not guarantee a better return than lump-sum investing, but it does lower the emotional burden of getting started and staying consistent.
The real advantage
The main benefit is behavioral. A recurring investment plan reduces the temptation to keep postponing action until the news feels comfortable.
The real limitation
If you already have a long-term lump sum ready to invest and can tolerate volatility, spreading it out can also mean more cash sits idle. The right choice depends on psychology as much as math.