But isn't the conventional startup wisdom "Don't worry about people stealing your idea, if your idea is any good you'll have to shove it down people's throats"?

If your idea can be so easily stolen, no one will want it because others can also steal it. Also, someone has probably thought of it and tried it. Also, it probably means your vision not ambitious enough to be a unicorn, and you would have better spent your time climbing a corporate ladder.

That said, there's wisdom in not assuming that VCs want your company to succeed, even if you get funded by them.