>> You don't know what you're talking about.

I can assure you I am intimately familiar with the entire process.

>> It means you need to fly back to your home country for a few days for the interview and then you get your GC on the spot.

Not necessarily. That's the best and most optimistic scenario. I know of people who have waited weeks, even months. It depends on a lot of factors. And now there will be a lot more people booking interviews at every consulate so expect wait times to skyrocket.