I think there's something about both the myth of the unicorn and of the hero founder/CEO in tech that forces a push towards legibility and easy narratives for a company - it means that, to a greater degree than other industries, large tech companies are a storytelling exercise, and "giant corporate blob that sprawls into everything" isn't a sexy story, nor is "consistent 3% YoY gains," even when that's translating into "we added the GDP of a medium-sized country to our cash pile again this year."
Every time a CEO or company board says "focus," an interesting product line loses its wings.
It's because the storytelling needed for Wall Street. It's the only way to get sky high revenue multiples, selling a dream, because if you're a conglomerate all you can do is to sell the P&L - it's like selling an index. If you have a business division that's does exceedingly well compared to the rest, you make more money by spinning it off.
I think Asian companies are much less dependent on public markets and have as strong private control (chaebols in South Korea for example - Samsung, LG, Hyundai etc).
If you look at US companies that are under "family control" you might see a similar sprawl, like Cargill, Koch, I'd even put Berkshire in this class even though it's not "family controlled" in the literal sense, it's still associated with two men and not a professional CEO.