The difference between wheels assembled with various components and wheels made with components designed to work together is great. The wheels are in fact a complex system in which every single component must work in harmony with the others and in a balanced way to bring out the best in each one. It is a balance of spokes, hubs, rims and nipples and each component must be suitable for all the others.
Here we see the difference between good wheels and very good wheels. Companies that spend years designing a wheel system rather than taking parts here and there and assembling wheels get much better products, both in terms of performance and reliability.
The wheels are in fact among the most stressed components of our bicycles and, if in this system, everything is not balanced, it takes very little to make them break, ruining the ride or maybe even the trip.
In fact, a wheel system designed as a whole requires that every single component is made to work in a uniform way, whether pedaling, braking or cornering, therefore with very different stresses. Spoking is the basis for the transmission of forces to the rim and consequently to the tire and the ground, and a rim with a non-optimized spoking is more unbalanced in terms of tension, just think that a normal rear wheel has a transmission side tension of about 110 kgf and disc side of about 60 kgf, but which must work well both when braking and when pedaling. In fact, guess which side is the most frequent breakage of the spokes? The exact left. In the wheel systems conceived as a whole, in fact, we find distinct spokes for each side of the wheels, according to the task it has to perform and the forces to which it is subjected, this allows to increase reliability and performance.