Meaning of "Point Blank Range" in the final battle of RoTJ?

While commanding the rebel forces against the Empire at the climax of Return of the Jedi, Lando responds to to the Death Star's activation by order the rebels to engage the fleet of Imperial Star Destroyers.

From the script:

LANDO (desperately) Yes! I said closer! Move as close as you can and engage those Star Destroyers at point- blank range.

In modern English, "Point-Blank range" refers to the distance at which projectile weaponry is close enough to its target that it is unnecessary to compensate for gravity. Since there is only microgravity in space and laser-based weapons would never be noticeably affected by gravity over the distances present in Star wars space battles, what does the term "point-blank range" refer to in the above excerpt?

If no pre-established explanations exist I'll accept well thought-out speculation.