Probably because those people who use the app most do not care about memory usage. Everytime somebody complains about how resource-hungry Slack is, it usually c

Probably because those people who use the app most do not care about memory usage. Everytime somebody complains about how resource-hungry Slack is, it usually comes from a developer. I rarely see project managers or designers or even clients complain. And, looking at the company I work for, the developers channel is the one with the lowest usage. This is why Slack became successful: it works for the people who need it most, not because it is very resource-efficient or well coded.