Skype for business is bad, you can't do simple things like share a file through the chat, you have to send an email attachment.

I have stability issues with Skype for business, but I share files daily with colleagues. Are you sure that's not some restriction put on by your IT department?

That might be the case :)

Yeah, there are some glaringly simple things Skype For Biz has trouble doing. Try to figure out how to view your chat conversation history.

The established standard UX across IM apps is that you click on the contact you are interested in, and scroll up in the chat window to view your old IMs. Not on Skype for biz.