I am just wondering what the advantage of self-tapping screws would be as compared to normal screws. Does it fasten more strongly? I know, with most self-tapping screws, pre-drilling can be skipped. Is this the only advantage? Or, is there any other advantage?
Not having to pre-drill is the benefit, and that's actually a huge benefit in terms of time and labor.
If you're pre-drilling anyways, then there's no real benefit.
Well, I would say the biggest advantage is not to have to tap the hole, since they're self-tapping, that's the whole point. To tap the hole you need to drill it first, so 2 advantages, but tapping takes longer than drilling, so that's the biggest advantage in my opinion.
There are both thread forming (machine screw) and self taping (sheet metal) screws that some call both types self tappers. As far as holding strength with the same size and thread pitch there is no difference in holding power for the same number of threads in contact, self tapped are faster and the correct drill point size built in so the "pilot" size is always correct is an advantage to predrilling when the drill bit is dull or gets broken.