The original poster asked what benefit breaking them up would have, they didn't necessarily ask for a benefit that's something lots of Americans would see as positive. America and its technology companies aren't super popular in many parts of the world in recent years, and people unfond of it would welcome progress in AI technology becoming less concentrated in the US. Maybe a more left-leaning Senator like Warren might see some benefit in power being more evenly distributed globally, rather than concentrated in a few big US tech companies.
I'm definitely left-leaning economically. I also am very much in favor of giving developing nations a chance at competing with our economy.
However, I would go more or less the opposite direction of what you're suggesting. I support allowing American companies to produce jobs on foreign shores _provided those companies follow American labor laws_. I'm in favor of pro-labor regulation and I'm also in favor of free international trade, but not where the latter is at the expense of the former. A totally free world market would circumvent our protections at home.
All this to say, I wouldn't really call what you're suggesting a benefit by any view.
Interesting platform for a US presidential candidate to promote regulations against US companies to promote world corperate “fairness”.