I am afraid you are having a huge misconception. Force balancing and moment balancing are two independent things. If you ensure force balance on a body, that doesn't imply that moment will be automatically balanced. A body which is in static equilibrium (like in your example) is balanced in forces and moments both. If you assume that there is some moment about point A and use moment balance to find that "assumed moment", forces will still be unbalanced.
If you draw forces correctly on a correct positions, where they are actually applied then you will get complete consistent picture of both moments and forces. Force balance doesn't require any information of positions of application of forces, it just requires only the forces. But moment balance (as it is $r\times F$) , on the other hand, requires the vector $r$ i.e. distribution of forces on the body i.e. the point or region of application of forces.
What happens at point A is: There is a distribution of forces at point A because Point A is not actually a point, it is a small region where forces are distributed, generally non uniformly. Now we don't know how the distribution of forces is. So what we do is just a simple trick (This trick can be justified using simple mathematics of cross products) : We say that, ok we don't know the distribution but we do know that the forces will produce some NET FORCE and a NET MOMENT about point A. And so we replace that unknown distribution of forces by an unknown Net Force and an unknown Net Moment. So you can solve for them by Force balance and Moment balance together.
But after doing this all, the distribution of forces on A still remains unknown and luckily no one asks that in problems/assignments/exams.