I think is funny, because is not the first time I hear about microsoft employees not using the company products.

I worked on a project with some microsoft engineers to create a chatbot plugin for Salesforce, using Microsoft Power Virtual Agent, and the comunication tool they used was Slack and not teams. And I was obligated to use teams because of the consuting company I worked at the time.

And also the version control they used at the time was I think SVN, and not TFS.