Multi armed bandit algorithms have been used forever to optimize ads, websites, newsletters etc.

Here is an article from 2013 that describes Googles Multi Armed Bandits algo integration into Adsense:

https://www.cmswire.com/cms/customer-experience/google-integ...

The first time I stumbled across the term "Multi Armed Bandit" was when I read Koza's "On the programming of computers by natural selection" in 1992. When I later got involved in e-commerce projects, it was immediately clear to me that this was the way to tackle the involved optimization tasks.