Being technically the best (or the best in 'freedom') doesn't seem relevant to anyone.
IP, TCP, SMTP, HTTP, these are fundamentally technologies of federation. They succeeded and continue to succeed spectacularly. However, with the commercialization of the Internet there are much stronger countercurrents. I still expect federated solutions to succeed, but adoption will be slower and punctuated, and in the interim there'll be countless proprietary also rans.
I think you can see some evidence of what people thought were development machines by the fact that Lisp Machines only seem to have been NFS servers, not NFS clients.
I totally get the value of a non-corporate, non-centralized solution. It just needs to have at least as good of a UX for me to switch back to using it.
https://www.gnu.org/philosophy/open-source-misses-the-point....
> A pure open source enthusiast, one that is not at all influenced by the ideals of free software, will say, “I am surprised you were able to make the program work so well without using our development model, but you did. How can I get a copy?” This attitude will reward schemes that take away our freedom, leading to its loss.
> The free software activist will say, “Your program is very attractive, but I value my freedom more. So I reject your program. I will get my work done some other way, and support a project to develop a free replacement.” If we value our freedom, we can act to maintain and defend it.
Relying on Slack, Github and what have you is clearly not to "get my work done some other way, and support a project to develop a free replacement.” It aligns with attitude exemplified by the "pure open source enthusiast".
If you think that you can't do free software development without relying on all the capabilities of Slack, then the honest thing to do is to quit and spend the rest of your days just working on proprietary stuff. You obviously prefer the solution which has features over any other concern, so why would you waste your time having anything to do with free software?
Richard Stallman obviously used proprietary software. But not past the point when he had replace it, even imperfectly: "I began work on GNU Emacs in September 1984, and in early 1985 it was beginning to be usable. This enabled me to begin using Unix systems to do editing; having no interest in learning to use vi or ed, I had done my editing on other kinds of machines until then." [https://www.gnu.org/philosophy/fsfs/rms-essays.pdf] This tells us that Stallman used Unix. Well, why wouldn't he have; what other practical way was there to code anything? (One supposes he could have started from the bootloader on up, like the Unix guys before him.)
Stallman wouldn't use Unix today, since it has been replaced by free software, and he wouldn't use arguments like, well, such and such proprietary Unix has better memory management or faster I/O, so I will still use that.
If you're using things like Slack or Github without the slightest intent of working toward replacing them, yet using them for free software activities, then that is a comically conflicted position.