It depends. A squad weapon as defined by modern military minds wouldn’t be a siege weapon, it would be a squad operated machine gun most of the time.

The ballista first and foremost was a siege weapon operated by multiple people.

Which part do you count as more important? That determines the answer imo.

Ultimately, the power of the ballista was adding range that forced an unlearn choice: continue taking intermittent ballista fire or move forwards into your own range.