This incompetence excuse puts YC in a bad spotlight too, because it makes them look like they are funding people with exact zero software development experience.
In a twist of fate, YC itself seems to be gamed like those broken companies.
So this is the third counterintuitive thing to remember about startups: starting a startup is where gaming the system stops working. Gaming the system may continue to work if you go to work for a big company. Depending on how broken the company is, you can succeed by sucking up to the right people, giving the impression of productivity, and so on.
This is what happens when you have people without sufficient domain experience making decisions.
Being a great software developer does not make you a lawyer (not even a bad lawyer).
That is why when such a marketing claim comes up, the first question to ask is from which base they built the respective product in 4 days, and which kind of additional value the respective company added during this process.
By your argument, I can just torrent moviez and appz because I'm not a lawyer and can't be bothered with minutae of copyright law.
Indeed, there exist people who argue that in many areas law has become so complicated and unclear what is allowed or not that you cannot thus expect from ordinary citizens to obey the laws anymore - even if these citizens are willing to.
Thus politicians do have an obligation to make the laws as clear, logical and comprehensible as possible, otherwise they loose their legitimization of expecting citizens to obey them.
That's no excuse for a VC-backed startup just ignoring it and YOLOing their way.
This actually disincentivises small creators (open source maintainers and contributors, in this case) from participanting in the very thing copyright is supposed to foster.