There was a big "Slack is where work happens" campaign, on billboards and expensive full page newspaper ads etc. By the same token that would also seem to have little purpose.
Maybe these kinds of ads are made as memes to be repeated uncritically by decision makers with little specific expertise, or something like that
The “EVs are good for the environment” ads are for the consumers, many of whom haven’t made their minds up about which car to buy next. People have made their minds up about whether they like remote work or not — see every HN thread ever.
The employees don’t need to be advertised remote work software. They either like remote work or they don’t.
An ad for “Slack is good for the environment” doesn’t change anyone’s mind.