This hurts readability of code with lengthy expressions. Knowing the target of the assignment is usually more important than the particulars of the expression when you're skimming unfamiliar code. Having the variable pushed out to random locations on a ragged right side isn't helpful.
One of Ruby's philosophies is to provide multiple ways to express the same fundamental operation so that it can conform to your thoughts instead of forcing your thoughts to conform to it. You can still do it the old way where it makes sense. Whether this philosophy is helpful or harmful is another debate.
If you've seen a method one way many times while learning, then see a synonym, you end up having to search up docs to make sure there isn't some subtle difference.