Would disagree with this. Communities I've been a part of, especially when we were back in the old day of IP.Chat available and today with shoutboxes, members would ask worthwhile questions in chat, and they become lost forever. So much so, on my own communities, I had to post warnings on the page telling them to create a topic for any questions on their cars (being a car site). Then completely disabled IP.Chat entirely due to members not understanding the differences.
Even for a brief period here, we had chat enable and people went in to ask questions about their community for support.
The more avenues you offer for discussion, the more you are downgrading the long-term content options which take thought in putting forth and people will gravitate towards the "easy" non-thought provoking one.
Kind of a separate use case for these players as they are more private focused and not entirely based on marketing their clients' content but communication between colleagues. Unlike, a community, where you're not selling content, but it is pretty much your product to offer and market to get more members.
We understand the usefulness of chat, as we use Slack as a company but still use an internal community for a knowledgebase, product discussion, and project management. Think in the terms of community, as Matt mentioned, chat is weak and potentially pulling content away from the community's usefulness.