No offence, but Sheryl heads up sales and ops (the head of Sales, David Fischer, reports to her), and will go visit big clients to sell them on FB ads/new products (of which IG was a good case).

I'm aware that Mark (he doesn't like zuck anymore, apparently) thinks that, but he focuses on product much much much much more than monetisation (there's an apocryphal story that suggests he said that ads weren't part of his vision for FB to an internal sales conference in about 2009-10).

Finally, I would credit the engineers in Ads a whole lot more than Mr Weil (to my recollection, all of the stuff that ended up making IG money was in place before he joined).

Source: worked for FB for a long time.