[TeMPOraL]

Let's aim for integration on equal footing, then. No special APIs for vendor only, and no ToC clauses prohibiting third-party clients/integrations.

I don't know how to work around the "COM problem", though - IIRC, your product can have just as deep integrations with Outlook & Office as Teams has, if you're willing to throw man-hours at dealing with the clumsiness of COM. This understandably advantages a company with lots of money to spend and direct access to people who develop the platform. Some non-MS products still manage to ship with deep integrations, but in my experience, they tend to be fragile.

That said, I feel it would be a tremendous help for both competition and integration, if some form of "can't restrict access to a service to vendor-owned clients" clause entered the law.

It's kind of my problem with products being turned into services - service providers currently have way too much power over their customers/users.