Better tools for kernel developers

Outlook is a Microsoft Exchange (as opposed to "email") client, requiring you to go all-in on Microsoft infrastructure on the backend if you're going to use even a fraction of its feature set. It also requires use of non-Free operating systems.

Both of those make Outlook a complete non-starter before we even get to feature sets.

I'm in this for the Four Freedoms, and I put my money where my mouth is.