persistence, history, search, rich formatting, image previews, synchronization between devices, usable mobile clients, group/here/channel mentions, channel directory/search, channel descriptions, file upload/sharing (XDCC is not this), multi-line/expandable messages (eg, paste code or logs without flooding the channel), user status (away/DND).
Some of this can be approximated with bots, of course, but there's a lot of extra work then required to make that work (namely, setting up, writing and maintaining the bot). Some of this can be done client-side, but then you have inconsistent experience.. you don't know if the other user is going to get the image preview or if their client understands markdown or some other formatting, or is going to interpret and display your message using some other markup format. Some of this you can also work around with one of those persistent IRC connection proxies, provided each user gets one and that is also maintained by somebody.
Eventually someone packages this stuff all together for simple deployment.. and basically creates a bad clone of Slack, but with 10x maintenance requirement and so many more things that can break.
For example my app https://quasseldroid.info/ which requires you to run the https://quassel-irc.org/ bouncer, but provides all that. As well as IRCCloud and Weechat-Android, which are also very awesome and provide a similar amount of functionality.
The other features are atm a work in progress.
I wish I could do more, but in the end, I’m just a single developer improving the usability of a single app in my free time.
For open source non-centralized solutions to compete with the proprietary options, you need lots of devs and even more funding. Matrix/Riot.im has that, and even they aren’t close to where Slack is. Most of us IRC devs are either getting nothing, or, as e.g. in my case, the donations don’t even cover the server costs.
In the end, if people want open solutions to grow, they need to put their money where their mouth is.
I hate Slack for open communities as much as the next person, but IRC or fixes on top of it aren't really the solution.
Are we complaining about price or are we complaining about proprietary services?
Doesn't IRC file sharing involve directly connecting to individual users to transfer the file, instead of those users choosing to download it at their leisure? And if you happened to be offline at the moment the user shared the file, can't you never download it unless you ask them to resend? For large, asynchronous groups, that is untenable. Slack's file sharing works because Slack hosts the file.
Also, basic messaging features are indeed missing from IRC. How do you do a private group chat? Like an SMS group thread? Doesn't it only support channels and then individual 1:1 DMs? Slack has ad-hoc group DMs. On IRC you'd have to make a new channel every time. It's like getting a conference room every time you want to talk to more than one person at once.
Slack also does voice and video calls, and screen sharing, and it's really quite good at it (feels light, not bloated). Sometimes talking with someone needs to turn into a face-to-face call.
Yep.
> there are surely ways to solve that
Most common solution is to use something else.
You could say IRC could do anything any other chat program does, but it doesn't.
I guess it lacks persistence and access to history? But there are surely ways to solve that.