For example, Motorcycle might also inherit special methods for dealing with two wheels, ... Some degree of "IMO" here, but in C++, multiple inheritance is generally an indicator of flawed design.

So they cut multiple inheritance from the language (just as they cut operator overloading). The designers’ extensive C++ experience taught them that multiple inheritance just wasn’t worth the ...

With multiple inheritance you might be tempted to say the Pegasus extends Horse and Bird because you've classified the Bird as an animal with wings. However, Birds have other traits that Pegasi don't.