That is wrong, just nonsense.
DO drizzle oil on the rising dough, as you are dimpling, as the recipe said.
1 1/2 cups of oil is just gibberish. I did not bother reading the whole thing. That is a made up thing on their part.
You should top it as you please once it is all spread out, risen or rising, etc. You can just sprinkle on salt, or salt and rosemary. You can put some olives on it. Or some roasted garlic. Some herb oil (haha, not 1 1/2 cups). Bear in mind that if you put a lot of wet things on, like caramelized onions or tomato sauce, you will lose some rise.
I do not know what you planned on, thought about or intended, but for a nice focaccia, served with a meal, I like rosemary and salt.
If you put some slices of mozzarella on, followed by tomato sauce (in that order helps it rise more), then you suddenly have a very nice Sicilian pie.
But, you are correct - no 1 1/2 cups oil, that would be drowning the poor thing........