There is so much business software out there and ecosystems that have evolved around it. Systems still running cobol on IBM mainframes; or, more "modern" stacks like Java apps running in IBM websphere. There are relatively small numbers of HN reading folk that went to some of the best CS programs and/or work(ed) at FANG caliber companies (whatever you call them now). The rest of the software engineer types are a diverse crowd and turning to IBM Bob might be more natural than some creepy looking orange starfish offering. That's my hypothesis anyway.
I'm sure tons of companies have retainer spends with IBM for software, hardware, consulting, etc., and this is another way for their corporate clients to spend down / increase their retainers faster