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The status quo was seperate software developers and software developers in test, and nearly equal numbers [1] (I haven't read this book, only the description, but seems authoritative).

The new normal changed around 2014, as described in this Ars Technica article [2]. In order to ship more stuff, more quickly, Microsoft eliminated the developer in test roles, removing the bottleneck of a specific role in charge of quality and hoping to diffuse the responsibility.

This addresses the 'fired all testers' part of your quote. I don't have references on the 'scrapped their testing hardware', but I imagine most testing hardware was maintained by developers in test, and when their positions were eliminated, they may not have had anyone to transfer the hardware to.

[1] https://www.amazon.com/How-We-Test-Software-Microsoft/dp/073...

[2] https://www.amazon.com/How-We-Test-Software-Microsoft/dp/073...