But what does He lead with? He leads with forbearance. But His forbearance is not limitless. Let's get that straight.
He had reached that point where forbearance was no longer a possibility. It had gotten so bad that He did what this commentator wondered about (why He hadn't done that earlier). He just went whoosh! and everything on the earth was dead except what was found in the ark.
He had a limit. He's forbearing, but He has a limit, and if we combine this with Matthew 24:37 where it says the end is going to be like the days of Noah, then we can surmise that this world is going to soon reach that limit with God again, and it's going to be a whole lot worse because this time it's going to be not just quick death, it's going to be three and one-half years of literal hell on earth.