Ad spends are measured and results are tracked.
The value of those ads is a function of how far the needle is moved.
It's only when the needle can only be loosely measured can this go awry. For example, in a brand awareness campaign, it's sometimes hard to measure effect.
If FB was reporting '80% viewed' when it was '20%' then it's basically fraud.
What some guy says at a conference about 'the future of ads' is almost irrelevant, people are saying things all the time, and even if companies were to allocated more budget there ... they should see the results for themselves and adjust.