While your statements aren't wrong, there are other large companies that are doing this type of thing. AT&T for example is running incubators and is on the order of magnitude of size as SoftBank.
Their $100 billion tech fund is too big for the kind of deals that the typical VC invests in. It's pretty clear this is going to have various strategies. Lots of small investments in startups, buyouts like they did with ARM, and these minority stakes in public markets.