Sparring requires one set of skills, while pattern performance requires another set of skills. While performing each activity requires many of the same skills, they each also require very different skills. Practicing one will not detract from the other, except for the training time that may be subtracted from one to allow time to train for the other. In fact, since many of the skills complement each other, practicing one may enhance the other.
If you can do one hundred full-motion pushups using perfect technique, you can easily do a few hundred of the half-ass pushups most people do. If you can perform a perfect full-motion inner forearm block in a pattern, it is easy to perform the block while sparring since it requires less motion and less effort.
However, the opposite is not the case. You may be able to perform a highly effective inner forearm block while sparring, but not have a clue how to perform the block in a pattern since, in the pattern, the block must be exaggerated and performed perfectly.
Pattern movements and one-step movements are used to build muscle memory so the nervous system learns to act and react with little to no conscious thought on your part. For example, you do not think about applying the brakes a stop sign. When the need arises, a trained body will automatically do what is required. Sparring a lot will accomplish much the same thing, but how many people are willing, or able, to spar as much as would be required to achieve the same benefit.