I think this would be an amazing idea. A bot people can add to their servers and use to subscribe to users, mods, games, groups, etc, per server, that the bot would then post a link to any updates from them as well as being able to link your Moddb and Discord account through the bot (or maybe just in general, through Discord's built-in account linking) so the bot can recognize who is from Moddb across multiple servers and acknowledge, reward, or whatever, people accordingly. Having features like Discord-wide announcements from Moddb through the bot, having some form of backup communication in case the site is down, applying Moddb-based ranks, and much more. And then maybe via PMs the bot can also give you your personal on-site update feed too, so people can prefer to have their updates be sent via Discord instead of through Email or having to come onto the site to check. There is a lot of possibilities here. I think this also has some potential to help integrate communities of modders on Discord too.
Pretty much everyone on Moddb probably uses Discord, or has at least heard of it, to some degree and I think the Discord team would probably be more than happy to integrate Moddb like with Twitter, Steam, Skype, YouTube, and Reddit, and most major mods also use several of those services so having a Moddb and Discord integration would be largely beneficial to the people working on said mods. Lots of major mods also have Discord servers already, as well, so it seems only natural.