Amazing to see how Slack turned from something everyone raved about to something everyone is sort of annoyed with and critical of. Maybe that isn't that surprising for most products as they age/mature but it seems particularly acute with Slack.
I've found this quote extremely true, but not just with programming language but with all things. People complain about Slack because they use Slack a lot, so minor quibbles become a daily frustration.
It is when people go quiet about a product that you should really worry. They're either extremely happy or aren't using it, might be critical to find out which.