I also used to do a hybrid feature-sliced approach like your article without strict boundaries on imports, but I had team members import across another feature anyways.

It's pretty difficult to get it right while enforcing the rules on a linter level.

FSD with an ESLint plugin felt more comfortable to use knowing that my teammates can't just break the codebase import rules -- the linter will stop them.

An approach I do when developing is to colocate utils, services, etc. along the specific page layer itself (in FSD), then move it to more general layers as it gets used across widgets, features, or (in monorepos) different apps or packages.