Corporations in the software industry are often monopolies. They derive their success primarily from network effects - It has nothing to do with the quality of the software that they produce or their development efficiency; in fact, big corporations are the least efficient of all at building software. Even Google has admitted in the past to completely rewriting most projects every few years.
Clearly this is a sure sign that they're not developing software correctly... What normal company under competitive pressure can afford to constantly rewrite projects? Why then are indie developers and startups spending so much time and effort trying to emulate these big corporations and trying to use the same low quality tools that they use?
The open source tools produced by corporations are heavily marketed and seem to cause lower productivity almost by design. Perhaps they are designed to create some Kafkaesque anti-competitive moat around their products. Big corporations can afford to be inefficient. Maybe they they want to make sure that everyone else is inefficient too. They don't want people to come up with more elegant solutions, they want everyone to be brute-forcing software development by the numbers, throwing hundreds of developers at every problem; because that's the only game they know.
They use their 'open source' software along with their monopolistic network effects to try to draw everyone into that Kafkaesque game.
The best open source tools are outside the corporate sphere but most people don't even know they exist because they are heavily suppressed by the corporate monopolies. They don't want to give up power.
They want to control the landscape of software development; to keep it at a low level of productivity that they are comfortable with.