Often people who dismiss philosophy end up going over the same ground philosophers trode hundreds or thousands of years ago. That's one reason philosophers emphasize the history of ideas so much. It's probably a mistake to think you are so smart you will avoid all the pitfalls they've already fallen into.

While I agree that it's important to avoid succumbing to these ideas, philosophy curricula tend to emphasize not just the history of ideas but the history of philosophers, which makes the process of getting up to speed for where contemporary philosophy is take entirely too long. It is not so important that we know what Augustine or Hume thought so much as why their ideas can't be right now.

Also, "the history of ideas" is really broad, because there are a lot of ideas that by today's standards are just absurd. Including the likes of Anaximander and Heraclitus in "the history of ideas" is probably a waste of time and cognitive energy.