Yeah see the people that are caring about this are caring because it has used up all of their available RAM, has pushed stuff into Virtual Memory, and it is causing performance problems for their system. Or, if they are IT, it is causing performance problems on their users' systems.

This is a pretty reasonable complaint when you're talking about a system with 2gb, and a chat application that uses 1.5gb of memory...or heck, a 16gb system when you have programs that legitimately need as much memory as you can give them and are being starved of it. Nobody would begrudge this usage if it was necessary for the task, but it isn't. Not even close.

Edit: Apparently this is better than it used to be, but there have been times when Slack also ate up CPU like crazy. Which, again, no biggie if you have plenty to spare, but when you don't...and even then, if you have plenty to spare, you're still going to be annoyed with Slack if it's eating all of your battery because the CPU is working really really really hard at...um...dunno? If it were mining bitcoin/monero without your knowledge or consent then at least it would be DOING something.

CPU nomming is a worse problem IMO, as your fans spin up and battery life shrinks. Other chat clients don't use notable resources, its suprising that Slack hasn't had much pushback over its heavy resource usage thus far.

"Virtual memory" is not a synonym for swap space: https://news.ycombinator.com/item?id=2937597

Thank you for the gentle correction. I will now also start using "thrashing" more accurately.

Is this really such a common mistake? What is virtual about putting memory onto a hard drive

In my experience, yes, I see the misconception frequently. I think it stems from Microsoft using the name "Virtual memory size" for swap space in earlier versions of Windows.