There's a lot more that goes on during flight instruction than people give it credit for and it's a lot more applicable to crew environments and dealing with people on a daily basis in the same sense. You are flying with different people frequently that have different habits, you have to modify your teaching and behavior to achieve a successful outcome, because they are all different. If you are any kind of observant person (kind of important when flying planes) you'll notice there are almost infinite iterations of how someone can "screw up" and you learn from each and every one of those mistakes. Sitting there observing landing after landing you realize what really goes on and what really contributes to aircraft control, rather than just reacting automatically because someone told you to do so. You'll experience people trying to put themselves into descents and approaches without being prepared, causing extreme task overload, you'll get to realize what it means to be the person ultimately responsible for a flight, you'll get to instill habits that will prevent future accidents.

As a captain, you'll be expected to train first officers, you'll be ultimately responsible for the flight, you'll be required to deal with all kinds of different people every day, you'll have to get along with many different first officers, cabin crew and passengers, you'll have to monitor the flight and your FO to ensure they are prepared to descend and make an approach, you'll have to build and shape the FO and ensure they are demonstrating the skills and behaviors that will make them successful pilots and captains.

This isn't all that different and the attitude of "I don't want to instruct, I just want to get to an airline" completely misses the point that you'll be required to do many of the same things and demonstrate many of the same behaviors/be put under many of the same stresses. If you can't handle it at the flight instruction level, you probably can't handle it in "real life", although they are both just as "real". I can appreciate flight instruction being distasteful because one was operating under the assumption that they sacrifice and get their certificates/ratings and then get automatically hired by an airline. Most people at first operated under that assumption and as the reality has become clearer during training and progression they come to see that each step requires at least several years. That's reality unfortunately.