Why is everyone moving away from subdomains for international sites?

I'm planning a multi-language rollout for a high-authority blog. Old school advice says use subdomains to keep things "clean," but lately I'm seeing everyone switch to subdirectories. For those of you who have made the switch: did you actually see a boost in domain authority sharing? Or is it just easier to manage?

I'm worried that if I go the subdirectory route, I'm going to create a giant mess of redirects that will tank my core English rankings. Help?