[Xeago]

Slack does quite poorly on accessibility, so anyone using assistive measures from their operating system or separate application (voice instructed navigation, screen readers etc) will have a much harder than the average blog post or mailing list.

[seattle_spring]

Based on the context, it's pretty clear to me that the parent comment was not referring to accessibility in the a11y sense, but more of the "Slack is a private company and therefore inherently closed and evil" slant.

[village-idiot]

I personally find Slack to be utterly abysmal at actually keeping information, stuff that scrolls up beyond the fold is effectively lost. Maybe that's what GP meant?