Because the rest of the business comes from Skype/Lync! Which was somehow an even larger atrocity.
Each and every tech worker I know loathes Teams with passion. On the upside it's like a common enemy so there's a small team building aspect to using it.
On the other hand, we're mostly using it for few page design doc, and have no idea what "final professional doc" or what "proper section numbers" are and why would anyone care.
But hard to point someone to the right place without decent numbering.