I agree with most of the thoughts on the "blue goo".
However once in a while a gasket might need a little help, say if the surfaces have been damaged due to PO getting carried away scraping old gasket off. It is always best to use a fine file to smooth off the damaged area, but sometimes due to the design of a part that is not possible. Such as the area like that cap for the oil filter with the surface recessed.
In that case if I was to attempt to use a silicone sealer I would apply it much like you would if using a coat of grease to make gasket come off easy in future. By that I mean apply it with a finger tip and only leave enough to "wet" the surface. If you can wipe any off with your finger then it is too thick!
I would rather deal with a slight leak that needs washing off once in a while than risk sealant getting someplace that stops flow of oil! If put on as heavy as it looks in the above pictures it is very common for the silicone to push parts of the gasket out of place causing an even bigger leak than if nothing had been done.