The power of having a bank account, of moving funds around, of signing contracts, etc.
Before that, companies had to have everything attached to a human, not the company. So the human was responsible.
You are so used to it that you think it's normal, but it's not.
It's a concept we have created: that companies can act in their own name, like they are actually something concrete.
But when we did that, we failed to give companies expiration date, something like inheritance tax, the equivalent of prison and so forth.
Something that doesn't exist, a concept, enjoy many things a concrete human can do, but won't pay nearly the same consequences.
In fact, it's sometimes in the title: limited liability company. It's by design.
And of course, it allowed humans to do a lot of things without risking to lose all their life if they failed. But we went to far and now, we have companies that can enjoy all those benefits but with much less limitations than the humans counterpart.
It makes them too powerful.