Facebook Messenger Integration (DMs, not just site)
Let me sum up why this is a problem when you are doing client acquisition on facebook (in facebook groups etc.)
Currently, from what I know, you can only use HubSpot with Facebook PAGES, not with a profile.
The problems with that: 1. On many groups it's not allowed to join as a PAGE. 2. It's weird when you interact and write with people on a group that has "normal people" as a page (your company), it might even get you banned from some groups. It's necessary to interact to build relationships.
This makes it impossible to use HubSpot as a CRM to track those leads, schedule follow-up, and so forth.
Facebook messenger gives no option to add notes to a contact etc. So this would be a big plus. There are A LOT OF ONLINE COACHES and service providers doing marketing via facebook. So looking into this might be a good thing.
Facebook Messenger Integration (DMs, not just site)
You mean it is possible to manage all FB messages of an account via HubSpot? Or do you mean Facebook messenger is better on desktop (to which I agree).