I disagree.
Corporations, in practice, aren't that. They are not disposable in practice. Large companies dominate their markets, expect to live forever, etc.
Innovations that don't happen within Google, microsoft, etc... those innovations don't happen.
This isn't an absolute statement. Innovations can happen outside and new companies can be founded. We went through a period in internet-based innovations where a lot of innovation happened outside of existing large corporations and became their own giant corporations. That's not a long term norm though. That reality was largely driven by really low capital costs. These days, new internet companies raise a lot more money... mostly to pay for advertising that goes to google and facebook, who control access to users.
More likely than innovation outside of existing companies gets bought into bigger ones.
Consider Tesla. Obviously Musk's abilities played a big part. So did his bank account, his ability to raise capital, etc. It takes that much force to innovate in that market from outside. Very difficult.
I think it's reasonable to ask why existing car companies couldn't pull off anything like it. There are incentive/incumbent reasons, but I don't think these are the whole story.
I agree that innovation should and could come from outside big corporations. But, the reality is that resources, market power and such are highly concentrated within large corporations. There isn't much space to operate outside of it. We can't expect a sub-1% section of an industry to do all the innovation... outside of rare examples like the internet circa 1995-2015.
Also, consider that tech giants are a lot more innovative than incumbents in other industries, largely because of the pressure from small companies and their relative youth. Trains, Planes, Cars, Roads, Banking, smelting, etc... these industries are not like that. Nothing at all happens outside of large corporations, innovative or otherwise.