I'm very well aware of this, but this doesn't necessarily mean that budget planning will be done completely independent across multiple different channels. We already have observed a significant fraction of search advertisements budget has been moved from Google to Amazon as Amazon becomes a more effective ads platform. In fact, nowaway this becomes a much more attractive option since Amazon now owns literally everything from advertisements, auction, optimization and measurements in a single platform.
> in many areas with deep-pocketed investors who think they'll eventually turn profitable Google actually takes more than 100% of potential margin.
Most of the Google's largest advertisers are big, conventional companies with a strong cash flow, not those burning the money from investors. They really care about incrementality, efficacy, measurement and performance. Sure, you can probably burn a few million dollars without a good reason but you cannot spend x100 like that.
That is the point I 100% absolutely disagree with. Ask any digital marketer, most of them see FB and Amazon as serving different purposes than what targeted search ads do. If you put 'Bing' or 'DuckDuckGo' I would agree with you, but in that case you'll find that the way Adwords bidding work that Google pretty much already takes a huge portion of potential margin - in many areas with deep-pocketed investors who think they'll eventually turn profitable Google actually takes more than 100% of potential margin.