Is there a way to specify the % of income that is allocated to cash holdings vs. investments? The modeller seems to assume that I will keep all future income as cash, which seems unrealistic.
The people who build FB's ads platform have their performance judged by metrics like revenue, eCPM, and internal relevance scores.
Building capabilities to add arbitrary human-defined rules into those optimization functions only makes their jobs more difficult and is a drag on hitting team targets. I'm curious why you think they're incentivized to do so.
IMO large social media platforms are actually much more capable of running these experiments than academics. (Disclaimer: I work on ads at one of these companies).
Platforms can accurately determine who engaged with an ad (basic logging on their sites), they have infrastructure to create statistically balanced ad experiments, and can also accurately determine whether a conversion happened (either through a conversion pixel or through data brokers).
Running these tests on behalf of advertising clients, or for internal research is fairly standard. If we couldn't prove statistically that our ads were working, I would have left a long time ago.