Think of it this way. Did the Web Browser need to be a proprietary closed protocol in order for the massive improvement over Gopher/WAIS or other end user hypertext information systems back then?

No, Netscape/Mozilla didn't need to "own" HTTP and HTML completely, and turn the Web into a giant App Store in order to innovate in the Browser client, neither did Google, Apple, or MS. At various points, proprietary extensions were tried, and either failed, or got standardized when they became popular or proven their need.

All Praise to Slack's UI, I love all the flourishes, like auto-detection of paste of code bits and offering to create snippets. I get it, I really do.

I just don't think we need another messaging platform owned by a single company.

Actually, many features of the modern web (DOM, XmlHttpRequest, box-sizing: border-box) were implemented by IE first.

Unfortunately it's not in the best interest of anyone capable of engineering open/distributed platforms to actually do so. Why would they? It's way easier and more profitable to create something on your own terms, something you can control. I would risk that it's better for the customer.

People are flocking from WordPress to SquareSpace, from self hosted SMTP servers to Google, from private hosting to cloud hosting.

Is this a good thing in the long term? I don't think so either, but doing it any other way would be heroism and we are short on heroes.

I agree, but you can't blame them for trying to stretch their monopoly imo

I think you're missing cromwellian's point: you could have made the same thing while upholding open values.

For example if it was a rich client based on IRC, I could join in on a chat without being a slack customer. I could also be a customer of a competitor that would offer something similar, but more tailored to my usage. Now that would move the chat ecosystem further.

But that is not happening, because Slack's business model is hegemonic: they want everyone to use Slack to maximize profits.

But then you would need to handle all the trouble that come from multiple clients. What if somebody makes a CLI client that does not support file transfers? The experience of official client's users would be worse because now they can't be sure that the other side can do the same things they do.

If the protocol were to be upgraded then one would have to wait for all of the vendors to support the new features or we would end up working with the common denominator. Real world examples are hardly scarce, we see this thing in the open web with myriad (semi-) proprietary extensions. Samsung has also hard time getting developer support for their unique features.

In the end, the end users would suffer because of inconsistencies. Open platforms are good, but in my opinion they will always lag in user experience behind well executed proprietary solutions.

Additional features that can't gracefully degrade would be a selling point for slack. "Your client does not seem to support video calls, we do, purchase an account here". When it comes to file transfers, a simple link to download the file from slack.com is a good degradation example.

Once Slack is installed and the norm, you lose some choice. You're prisoner of the way they want chat to be.

I'm sure glad Firefox exists, because otherwise I'd have to hop in the Chrome bandgwagon and sell my data and habits to Google without a choice. The competition there goes further of course, as Mozilla upholds different values, and competing teams try to make their products faster and better.

And then, they fall. Look how Microsoft used to sell a product but now capitalizes on users' data. What will happen when Slack falls? What if I don't want my chat data hosted by some company, but in house, and my business partners use Slack? Where will the choices go?

There certainly are disaster scenarios that can happen. My point is disregarding that in favour of the general user experience. For me knowing that the person at the other side has all of the features I expect them to is great. This goes for support of file transfers or video but also for the fact that all of the buttons are on the same side. (I had to explain over and over where the Skype chat is because the Mac and Windows versions are so different).

If Slack falls then, well, we'll pay the price of migration, but seeing as it is a tool for ephemeral conversations I see it as less of a problem as migrating e.g. my e-mail.

Yes, we all know and agree with their statement, but it's also not what was being said.

UI is absolutely important to getting users on to a platform It's also a totally distinct issue from the network used for communication. There's no reason we can't have a good UX with an open protocol too, and that's what was being talked about.

Because it's a platitude that has been repeated ad nauseam, and we get it. The GP gets it. As he explains in OP's sister comment.