Despite all that data though, there's still very little in the way of a clear approach to figuring out cross-channel attribution, valuing view-throughs etc.
The technical strategies are pretty straightforward but it's all the business policies, silo'ed data, bad integrations/tech, privacy issues/constraints, and (the worst of all) politics and outdated thinking, that cause these issues.
Attribution isn't that hard, it's basic analytics and statistical analysis - but half the agencies don't have any understanding of math or tech and just use last click wins with some unreliable vendor and probably poor implementation which ultimately hurts everyone.
As someone who has invested countless hours reviewing attribution reports and has seen how it is handled by companies of all sizes (including up to Fortune 50 brands), I respectfully disagree with your statement that "attribution isn't that hard."
I have the fortune to also work with an incredibly bright Data Science team (several of whom have phenomenal stats backgrounds), and they all agree with me.
Many companies and agencies know last click has very real limitations. Likewise, for anyone that has started to go down the rabbit hole, you quickly find all of the other static models have similar limitations. Dynamic/data-driven attribution at the user path level is the way forward, and Adobe's econometric attribution modeling tools are the closest I've seen to getting it right. But even that has limitations (cost being just one of them). The free reports in GA and AdWords are a great start, but likewise have their own issues.
There are a LOT of variables in terms of sample sizes, data accuracy, inability to effectively isolate an experiment group due to other marketing efforts, etc. that all throw other major wrenches into this.
All of that said, I'd genuinely love to hear your solution for how to definitively solve attribution from an analytics and statistical analysis perspective. As much as I disagree with your statement, I realize I don't have all the answers, and if you have them, I (and many others) want to hear them.
Personally, I think this is the biggest challenge the industry faces right now. My gut says display and video CPMs are overvalued, but better analytics and better data are needed to really help advertisers answer the questions of things like "what is a view through worth?" or "how much revenue should I attribute to this display/video campaign?"
