It feels the opposite way to me. Microsoft bought a company with an extensive suite of IP that publishes a lot of games. Sony panicked and bought a company that has one franchise (Destiny).
When looking at Disney, I see a company that has bought a lot of deep IP catalogues. They've used that to really propel their future and get high-value talent that wants to work in those universes with a Disney-sized budget to tell their stories.
Activision Blizzard may have cost 20x more, but Activision is really profitable with a P/E ratio of 26 (at the $69B deal price). Microsoft's P/E is 33, Google's is 26, Apple's is 29, Amazon's is 58, and Netflix is 38 (even with the tumble in price). So Microsoft bought Activision relatively cheap compared to its earnings. Bungie is private so we don't really know what their finances are like. Activision's cheap price means that there isn't a lot of risk for Microsoft. Maybe you believe that Activision is about to crater and no one will want their games in the future. It's possible. It's also possible that everyone is going to get tired of the extensive IP catalogues that Disney has assembled. However, when the price is that reasonable, you don't need the same explosive growth to justify the investment.
So Microsoft bought a business that even if it just keeps performing as-usual will be a fine addition to Microsoft. It also has the potential to be huge for Microsoft with a deep IP catalogue, the potential for Xbox exclusives to help launch the next-gen Xbox when the time comes, the potential for cost savings with Azure infrastructure, and probably more that I'm not thinking of.
If Sony buys Bungie and just lets them do their thing, they might get some good games. But it seems like Microsoft wants to buy and pour some money in which seems like a recipe for bigger successes. We've seen it with some of Microsoft's recent purchases. They've poured money into GitHub and made it an even bigger platform. They've poured money into .NET Core and Xamarin/Mono to recapture developer mindshare. It seems like Microsoft is likely to take similar steps with their Activision purchase - and similar steps that Disney has taken with their IP catalogue.
It's possible that the small places Sony has bought have better potential, but Activision Blizard is a profitable company at a relatively cheap price which means that the purchase carries relatively low risk while still offering a lot of upside for Microsoft.