The key is in "on the surface". While the common usage of sudo is fairly straightforward, you me and most people use like 5% of it. The trick is in all the side shows.
Makes you wonder then why it does so much, if those rarely used features increase the surface area of possible exploits? This is just a question I’ve had about *nix utilities in general, since sudo is hardly the only tool with obscure flags and features
Because the long tail of features is useful to someone. Mind, I like doas for this reason, but having the more feature rich option available makes sense.