To better complete the ecosystem and satisfy the users needs, because on many sites users to want to chat, and they will find ways to chat.
It keeps the user within the Reddit ecosystem for their chat needs. This means longer amounts of time spent on the website, inside the app, and therefore more advertising data collection opportunities on those users, so they can better monetise.
I see many members on some forums sharing phone numbers so that they can SMS/iMessage/What'sApp each other to arrange BST deals and meet each other at events. Why? Because it's a better and more instant form of mobile communication for many of them than using the built in private conversations and they're guaranteed to get pinged on their phone when someone is trying to send them a direct message. And that's only in pubic, I know in my private conversations I'm often agreeing to take the conversation off the forums to a live chat platform instead.
For many communities, members want to share particular things with individuals or small groups of users instead of the entire community.
They want to be able to organise events and have a way to chat in real time in private with a small group of people to organise meeting up at these events, attend the event and then afterward take part in public discussion on the forum afterwords and share text, images and video from the events. Or they may just want to shoot the breeze in private with the friends they've made through the forum for an hour or two every evening. Or hit them up for a 15 minute live catchup once a week. It feels easier and more fluid doing this in live chat as opposed to private conversations, which feel more formal and like email.
I've got one of the live chat plugin's for conversations installed on my forum and it's mediocre, it's not truly live and is a bit of a bandaid, it quickly becomes frustrating and is a far inferior experience to using a proper chat interface.
What do we do? We nearly always end up leaving the site and taking the conversation elsewhere, to Facebook Messenger, What'sApp, Discord, Steam - now potentially even Reddit Chat, especially now that it's built into the App and we can live chat on mobile. And now we're back spending our time in the ecosystem of some other community platform of some for or another, and not where we started.
The requirements to build a truly all encompassing community platform that an admin can buy and launch and have all the features that many users want these days is changing. IMO it seems forums are lacking in a few important areas if they're to be true community platforms in 2018 and not just message boards.
Having a high quality native mobile app interface. Who cares if it doesn't look fancy or can't be styled, it's the functionality and ease of use for the user to digest and supply content on their phone that matter, along with push of course - Users want it and will use it, TT is evidence of this.
Having the ability to upload video to any post - Users want this, so so so many video posts in many of the Facebook and reddit communities I visit. No one wants to faff around with uploading to a 3rd party site and embedding. The upload button needs to be part of the reply box, offload the heavy lifting to a video hosting service or AWS and embed the result automatically.
Having a live chat/conversation interface on desktop that also integrates with the mobile app - Users want this, because PCs feel clunky compared to the plethora of well made chat solutions available, and are therefore using these other solutions instead.
An events system - for some sites, obviously not all, but it's a pretty basic requirement for many communities that have any kind of connection offline.
Admins will want all of these too if they were done right and they realised how much extra time users might spend on their site if it was all integrated. And if it presented them with additional and increased monetisation paths due the extra site engagement, features for user upgrades and new content types to advertise over (eg. pre-roll ads on video uploads).
By not having live chat, forums are driving their users away to other platforms to get the private chat experience that isn't available or is quite poorly implemented in comparison to what's available elsewhere.
By not having all of these, many users are tending towards using other social networks that do have all of these in one place and even starting their own communities on these platforms themselves.
