If you're a company of 10 or 20 people, you won't notice the problems. It starts to break at medium-sized business scale (anything over, say, 100 employees). You start to notice limitations in the UI/UX but also just constant bugs in calling functionality, split meetings, super laggy large meetings, slow navigation, and broken search.

It just feels like it wasn't built for serious scale from the ground up, like some after-thought Todo List app that was thrown in with Office 365 to tick a checkbox.