A considerable amount of the value of these companies is due to them being publishers. However, that's not worth as much to other publishers (first party or otherwise), who already have their own publication businesses.
Similarly, another large portion of the value of these companies is that they are multiplatform, with player bases on PlayStation, Xbox, Nintendo and PC. A first party purchase of those publishers would mean that some percentage of that player base would migrate, but the rest would be lost.
If you look at, say, Capcom, right now they have a market cap of ~US$6.5 billion. It would cost some unknowable amount (but higher than that) to purchase them. However, their actual value to Sony or Microsoft would only lie in their capacity as a developer of PlayStation or Xbox exclusive games. That would probably only be worth a few billion US dollars. Sony's recent purchase of Insomniac valued them at US$229 million, so here's a thought exercise - how much more is Capcom worth than Insomniac, to Sony, as a PlayStation-exclusive developer? 5 times more? 10 times? For anyone answering a number lower than 29 times, then Capcom's current market cap makes them overly expensive compared to Insomniac.
That's why with acquisitions, the focus of Sony and Microsoft has been on developers, rather than publishers.
Smart post, agree with your thrust here.
