I don't disagree with your reasoning. But I do however believe that constantly playing it safe with regards to the products they already have isn't always going to work in their favour. Sometimes innovation can be a good thing in any space or industry. Purchasing Start-ups by making false promises of a better future to the employees and then moving to shut them down because they supposedly didn't work with your philosophy or vision is not an excuse. Why purchase them and fuck over their independence in the first place? Microsoft can be creative sometimes, but they lack the drive and motivation to turn that creativity into something meaningful.
Sony got where they are in the music and movie industry through humble beginnings, just like everyone else. Today, their audio production products and movie mastering equipment are heavily praised and sought after by producers. Does that mean that they haven't made their fair share of mistakes and mishaps? Absolutely not. But they got where they got through steadfast dedication and unyielding motivation.
Did they not make acquisitions and purchases of their own, related to startups with novel ideas and creative concepts? Of course not, every big company does that. But at least the purchases that they made, stuck around for relatively long periods of time, enough to see the fruits of their labour and creative ideas materialise, most of those acquisitions are still around today and better than ever. And yes much like Microsoft, Sony also shut down a fair bit of the start-ups and studios they bought, albeit a much smaller number compared to Microsoft, who seems to be hunting mostly for the patents, trademarks and registered IP's of their purchases, than the actual talent.
Microsoft has the creativity, they just lack sufficient drive and motivation to make it happen. Being lazy and using only wealth and power to make things happen won't always work in their favour and they've been able to do most of the things they do because of extremely lax & loose regulations in their territory, a thing even the UK is trying to avoid, by strengthening their regulatory & merger laws to prevent big tech companies from having their way by flexing their infinite war chest to have their way.