If they AREN'T perpendicular, you need to multiply with the sine of the angle between vectors.
In statics classes, the NET MOMENT, much like the NET FORCE, must add up to zero. Why? Because if it didn't, the body would be accelerating. Pay careful attention to the word "net". What does "net" mean?
This doesn't necessarily mean that there AREN'T any moments, or that there AREN'T any forces. It is just that whatever moments there may be and whatever forces there may be must be balanced by the constraints.
A cantilever beam fully fixed can support against forces in both directions and all moments. Therefore, it will have a reactionary moment, acting on the beam, to constrain against the moments caused by the load forces.