Maybe "messy" was a poor choice of words.
A couple years ago, we did both hardware and software upgrades simultaeously. First, we replaced all aging Windows XP machines student's were using with Chromebooks and Chromeboxes. Second, we gave every student their own G Suite account (a change from student's being assigned generic "comp_xx" AD accounts every year if they were enrolled in a computer class). Now, every class is a computer class. Consequently, I've built out my G Suite IdP much more than AD, to the point where AD is stagnating, in terms of user accounts.
With GCDS, it's a one-way sync from AD to Google, and rather than export from Google and rebuild AD org structure with those exports, I'd just rather use G Suite as the native IdP. I hope I'm not alone in that. 🙂