My theory reverses your theory's cause and effect: King was a reverse merger that was very nearly a takeover of Activision Blizzard at the time. Zynga was thought to be the same for Take-Two (which at the time was particularly bloodied by bankruptcy-related issues and in a position to be eaten). The EA and Popcap merger is another one that was questionably a reverse merger/near takeover, especially in the way it shook up the executive board at the time. (I forgot about Popcap in the above summary because as a brand to themselves they've quietly sort of disappeared from modern mobile trends, but their logo still often shows up in EA presentations.)

In general, "lowly" mobile gaming still has more active players spending more real-world money at any given time. It's very hard not looking at the bottom lines of some of these companies, especially today's weird Activision Blizzard and not see "the tail wagging the dog" and mobile games effectively sponsoring and/or subsidizing development costs on every other form factor of videogame. The biggest exceptions seem to be Sony and Microsoft themselves, and Microsoft dabbled in mobile gaming over the years, has a big mobile gaming contractor in Arkadium (using the Microsoft brand for Solitaire and Minesweeper, among others, and generating some revenue), and does own one of the largest mobile games of all time (Minecraft) though people often don't think of it as such.

I think it also shows up in executive leadership and how F2P microtransactions hell has been infesting "AAA" and "AA" PC/console development for years now.

From my outside perspective of the industry: "Mobile games" won. PC/console games are the weird, "too expensive" afterthought for most of the videogame industry, subsidized by and beholden to the mobile games. The "gamer culture" that doesn't see most of the mobile games space as interesting or important and doesn't see mobile game players as "gamers" (or worse sees them only as "filthy casuals") is the minority out of touch with market realities.

Admittedly, that's a somewhat extreme perspective and there are plenty of exceptions and gray area and further complications. But whether or not you agree with that perspective, my earlier point remains that overall mobile games and PC/console games are inextricably linked by market forces and treating them as separate markets, and especially treating the mobile games market as somehow inferior, misses a lot of the forest.

(That [currently] Cold War between Apple and Epic has very real stakes, including for PC/consoles, and isn't just a silly "mobile gaming" problem.)