IMO it's too easy for competitors to create a similar level of functionality for it to be a standalone product.
If Slack charges too much, there's a host of free alternatives that can be used, meaning they have limited ability to increase prices.
Compare that to office suites. There's not that many options here and it's pretty difficult to build something that would have the functionality that enterprises think they want/need and compete with incumbants like MS.
The main free alternative (libreoffice) has had recent struggles with funding, due to the level of work needed to maintain and improve their offering
If Slack charges too much, there's a host of free alternatives that can be used, meaning they have limited ability to increase prices.
Compare that to office suites. There's not that many options here and it's pretty difficult to build something that would have the functionality that enterprises think they want/need and compete with incumbants like MS.
The main free alternative (libreoffice) has had recent struggles with funding, due to the level of work needed to maintain and improve their offering