Fair enough, and to my credit, I said I was guessing about the popularity of IRC vs Slack. And I wasn't defending IRC; I am a Slack user, and by choice. A quick search showed me that public IRC servers had ~503,000 daily active users last week, while Slack recently had over one million daily active users. I would further guess that the IRC users are more likely to have made that a choice versus the Slack users, who are more likely to have signed in to Slack because that's what their workplace uses, making IRC the more popular "choice" rather than the more popular "service", but that'd be more conjecture on my part, and in any case, my argument remains unchanged: popularity can in fact be a signal that something is better/easier for those that use a device or app or service. Examples to the contrary (BetaMax vs VHS, HD DVD vs Blu Ray, 8-track vs cassette) are interesting from an argumentative point of view (I really wanted HD DVD to win, FWIW), but that's just it: there will always be evidence to the contrary.
It doesn't make it a logical fallacy to say something is popular because it's superior for its audience.
It doesn't make it a logical fallacy to say something is popular because it's superior for its audience.