Earlier quoted context omitted.
I mean I love redis, but Amazon Google and Microsoft all probably have readily available in memory key/value stores at hand. Throw a little money and they can make it redis compatible, so we wouldn't have to re-write any code. Redis is great as an off-the shelf component, but it's not exactly rocket science to re-implement for a big corporation. So redis doesn't really have any leverage in my opinion.
It's all about branding and name recognition: they all profit from Redis via their cloud offerings. They have a strong incentive to support it and to have it as a viable open source project. Similar to other key opensource infrastructure. Then their cloud-specific solutions are the up-sell (and lock-in).
Which is why Microsoft's new drop-in replacement works with all those things. It could gain traction - who knows.