I thought I’d point out here, that I did get this working with scenario 3, as long as I included a signal on the far side of the station as well.
As for why someone would want to do this, it’s hard to understand when you see an isolated station like this. But if you have a 6 stop line, you might also put on an express train that only stops at 3 of them. First, middle and last. Skipping a few. At the stop they share, they might need to load at the same time (maybe your slow train is set to wait)
Again, you might also have different speed trains. A slow train, a fast train. I don’t know if the income is adjusted for arrival speed and things like that.