I could be wrong, but my sense is that ML has leaned Bayesian for a very long time. For example, even Bishop's widely used book from 2006 [1] is Bayesian. Not sure how Bayesian his new deep learning book is.
I stand corrected! It was my impression that many methods used in ML such as Support Vector Machines, Decision Trees, Random Forests, Boosting, Bagging and so on have very deep roots in Frequentist Methods, although current CS implementations lean heavily on optimizations such as Gradient Descent.
Giving a cursory look into Bishop's book I see that I am wrong, as there's deep root in Bayesian Inference as well.
On another note, I find it very interesting that there's not a bigger emphasis on using the correct distributions in ML models, as the methods are much more concerned in optimizing objective functions.
[1] https://www.microsoft.com/en-us/research/publication/pattern...