Does a ski jump prevent conventional aircraft use?

Why fit a ski jump if it appears to prevent other aircraft types from operating?

The ski jump is not the barrier; the absence of catapults and arresting gear is. The ramp lets STOVL aircraft launch more efficiently from a short deck.

The ramp itself does not exclude conventional aircraft. Invincible began as a helicopter cruiser and later received a full-length deck without becoming a catapult-and-arrestor carrier. The ski jump was then added so Harriers could leave that relatively short deck at a more useful weight. Conventional fixed-wing aircraft remain incompatible because the ship lacks the machinery to launch and recover them, not because the bow slopes upward. The ramp's benefit must be separated from the carrier architecture surrounding it.