Interesting to read this just as I join a new company and am using slack "professionally" for the first time (on an all-remote team). My thoughts so far have been basically the polar opposite of this post. I was previously in a FAANG where the only tool was the internal messaging platform, which in my opinion, left a lot to be desired. Slack search has been miles better, and has enabled me to get up to speed way more quickly by finding posts from months/years before I joined that are exactly relevant to what I was looking for. Nobody uses it to bug me, and in fact most of the "work" takes place off-slack in GH issues/comments, Jira, etc, but integrates with slack nicely. There is no expectation of immediate response from my manager or anyone else.
It seems like most of the article complaints are cultural, more than they are about the platform itself. Obviously it's still early days for my usage, but strictly evaluating the tool itself, it seems pretty solid. Definitely better than "unnamed but awful FAANG-specific tool".
And the "markdown" text input oh my. Rarely have I seen a worse markdown input than in Slack. Maybe on Bitbucket or Confluence it is worse. It is as if they have decided to not use any existing and perfectly well working markdown parsers, but instead get an incapable team of engineers to reimplement a bug-ridden one with missing features. One cannot even insert an image at any place in the message, but only at the bottom. That means one needs to refer to the image in the message, when otherwise one could have simply had the picture in that place where it is relevant. It is such a headache for anyone more familiar with markdown. At this point just give me a plain text input, that has any normal off the mill markdown parser to properly translate my text into a message.
Oh and they still have not managed to implement voice chat according to standards properly, so that it works in all modern browsers. While other more feature full chat programs like Discord had this solved for years ago, Slack is still the same old shit. Now I have to start ungoogled-chromium every time I want to enter a "Huddle" and navigate to their website, where they will bug me with their incessant popup asking me to use their desktop app, which I have to decline every. single. time. because chromium does not remember to block such popups from websites.
So basically Slack is quite crap.