Because different than the ARM chip also announced in the same Ignite event, Microsoft doesn't exactly "need" nor can fully utilize an AI chip. Google trains its foundational models (e.g. Gemini) on its own TPU hardware but Microsoft's is heavily reliant on OpenAI for its generative AI serving needs.
Unless Microsoft is planning to acquire OpenAI fully and switch over from Nvidia hardware...
None of this is really strange. It also wasn't strange when Google announced H100 systems while also pushing TPUs they developed. Microsoft has Jensen on stage because customers of Microsoft Azure demand Nvidia products. Customers of Google Cloud demand Nvidia products. So, they provide them those products, because not providing them loses those customers. It's that simple. Everyone involved in these deals acknowledges this.
In some ways, Microsoft was 10 years ahead, but they are terrible as an organization at proliferating research projects to production across multiple orgs.
I'm guessing at this point the ASICs make a lot more economic sense, though. :)
They're going to play a modified version of the old Rareware trick.
It's also a pretty great game to buy up OpenAI equity, which ultimately gets spent on Microsoft compute. Two birds, one stone.
[0] Microsoft tried to buy Nintendo very early on
Almost nobody in this game cares about profit right now.