The advantages touted when the system was relatively new where:

1) Internal halyard system, less drag
2) Ability to raise and lower the main on the water (yea right)
3) No slipping slugs
4) You don't pull the boat over on top of yourself trying to pull a tight new sail up.

Keep in mind when it became the standard there were a lot of competing systems, Hobie's flopper, halyard lock (it had a release and a lock line going up the mast), sky hook, a side halyard and some I never understood. The ring and hook works fairly well and is easy to maintain. In my attic somewhere I have a shackle lock that I was told "when it locks up flip the boat over and cut the shackle holds the sail with bolt cutters to remove all tension. It should release after you beat on it for a while"

The internal halyard were established as "the way to go" in the 80's and it still works. It thinks it's more expected than needed for most boats