Counterpoint being that Slack, for example, for all its faults, does not have ads in its chats.
If Anthropic is positioned as "thing for professionals to do professional work" then I think you just avoid this issue entirely. Fee for service. OpenAI trying to be the thing everyone is using won't work in that model, though.
Maybe there's a predictive market gamble starting about how long it will take Claude to follow suit if OpenAI starts making 9 figures in ad revenue.