In the bad old days when the weather was poor it was traditional for the captain to fly the aircraft to minimums AND then to land it. This meant that he was kept pretty busy and didn't always make a great job of it. Whilst this was going on the F/O didn't really do a lot except move the flaps and the gear.
Then some genius came up with the idea of the monitored approach. This meant that one pilot flew the approach to minimums and was programmed to make a G/A if necessary. The other pilot monitored the approach and was geared to looking for the runway and landing.
The next perfection came with which pilot did which. It was established fairly rapidly that it was better for the F/O to fly the approach and the captain to land. Simply put, if a very senior captain was making a bit of a mess of the approach then a very junior F/O might be reluctant to make comment whereas no captain would even hesitate slightly to put the F/O right.
I don't know who invented the system but I first saw it in BEA in 1964 and I have been using it ever since. All airlines that I have ever worked for used this system.