Someone did this on a project I work on (C#).
Utter nightmare. Loads of repeated code as new programmers didn't know methods existed, loads of extraneous DTO objects, lots of nested single line methods, massive code bloat. Hard to find what actually does stuff, hard to use built in editor functionality.
It's really not a good tactic imo.
I'm undoing it as I go, at one point after having worked on it nearly 4 months according to git I'd still had a net negative on total lines of code, having added a ton of new functionality.
Admittedly, it's one of those projects which has had a bunch of freelancers/contractors work on it, but I personally really don't see what it added to move the methods off the classes apart from confusion, code duplication and code bloat.
I see the need for something, on the startup + enterprisey projects I work on you always seem to end up with at least one mega class that ends up being a beast, the Order, Person, Customer, Job or Project objects are usual culprits, but most other classes don't need much past a few basic methods. I'm just not convinced this programming tactic is it having now seen it in the wild.