For as much as we all hate MS Teams with a passion: It is not arguable. It is superior. And Exchange and Outlook couples well with MS Teams which gives you a corporate chat client, teleconferencing, document sharing, etc.
That hodge podge of tools? It is someone's job to maintain that. Likely someone who is maintaining significant parts of corporate infrastructure and doesn't have time to work through what the 55 year old waste of space refuses to even try to understand but will instantly get blamed in meetings with the c-suite if that idiot can't figure out how to write an e-mail.