The problem is when a few most important apps require IE and even older IE mode. Yes, some personal apps won't work, so users can use Chrome for that. But then it creates a confusion what browser to use when. And sometimes it gets even weirder when such legacy app, that requires IE sometimes works better with Chrome (in some rare cases).. :) It is easy to say "just update your apps". Some are heavily modified 5+ years legacy SharePoint 2010 or older apps that can't be even easily moved to 2013+, not even saying Online. And in some cases legacy apps are enforced by government and you can't do anything about it. Enterprise Mode helped when moving to IE11 (and Windows 10 by making sites opened in Edge to forward to IE). Although i wish it would be a bit more admin friendly. I dislike doing GPO with registry modifications..