Ask HN: What happened when Slack didn't consolidate communication @ your office?

Looking for tales or advice about Slack not working out for your company.

My employer adopted Slack but only amongst certain groups — we are stuck in a limbo that spans generational understanding of modern tech and institutional practice that's hard to change. Reliance on both Slack and email, depending on the employee, is reducing focus and increasing the amount we all need to read just to keep in touch. Management is unwilling or unable to recognize the problem and define a default method of internal communication.

Anyone else work in a frustrating landscape like this? How did you move past it?