As an advertiser, yes, but on Google Ads you know that 90% of those will be fake ¹. And as a publisher on Google Ads you only get something like 1$ per 10000 impression ². Advertising directly on SO you know all views are not only legit, but also target at developers, so I think advertisers are willing to pay more. While most advertisers are paying per click, the whales only care about impressions, not clicks (TV commercials).

1) Measured by analyzing the traffic I got from Google Ads 2) That's what I get from Google ads as a publisher, but you used to get a lot more in the epoch, like $5-10 CPM