Further to that by sparring early, because begginers dont know how to move, dont have the right reflexes, strength, speed etc. They can develop bad habits, wrong reactions which end up being a set back later on when you do learn to apply it all correctly.
In my experience, sparring helps break bad habits, not build them.* It's one thing to drill a technique and have the instructor come over to nitpick that your elbow is in the wrong position. It's another thing to experience getting punched in the face or arm-locked and then realize it was because your elbow was in the wrong position. That sort of experience gives you a lot of motivation to clean up your form and listen to your instructors advice. Sure, students start out sparring their technique usually goes to crap. The more they continue sparring (with appropriate feedback and guidance, of course), the faster that technique improves and the better it holds up to pressure.
*(This depends on how the sparring is structured, mind you. I have seen schools where the sparring is set up in such a way that it probably makes the students worse, not better. Just about any training drill can be structured in such a way so that it fails to accomplish its purpose.)
Perhaps boxing is more natural to pick up
Wing chun typically is not the most natural feeling martial art to practice
This is a distinct possibility. Students may need more time to internalize the basic body mechanics in a less intuitive art before they can do anything effective with it. I'm new enough to WT that I will withhold judgment on the matter. I was able to use at least some WT methods effectively in sparring after just a few months, but I'm starting from a very different place than a typical beginner.
On the other hand, many of WC's origin myths include the idea that the art was designed so students could reach the ability to fight more quickly than in older systems, so who knows.
maybe there is less to learn in terms of individual techniques
Hard to say with regard to boxing. There are fewer officially distinguished techniques in boxing than in most arts, but they are explored in a depth equal to or greater than any art out there. If you were to name all the individual variations of techniques (ex. the many ways to throw a jab) and the subtle moves used by high-level boxers which don't have an official label, then the count might be higher. Muay Thai probably has a comparable number of individual techniques than WC. BJJ has many, many more individual techniques. All of these arts benefit from early sparring.**
**(There are a minority of BJJ schools which make students wait until they have a grounding in the fundamentals before they start free sparring. Usually this takes just a few months. I do know of one association where it takes over a year before the student is considered to have enough of a foundation for free sparring. That is an extreme outlier, though, and they do have the students work on semi-free-form "reaction drills" in the meantime.)
Without having refined the individual components to a high level and then learned to put them together its just a mess and can be very frustrating
This brings me to a term I've mentioned before, though not recently. It's a concept from engineering and computer programming called "failing gracefully." Basically the idea is that if a system has a flaw (as all systems do) and encounters a problem, you don't want the whole thing to just blow up and fail completely. You want the system to do the best it can with what it has and continue on.
One implication of this is that you don't want to build a system which requires perfection or near perfection in order to be functional. A system which works when everything is 99% bug free but crashes and burns at 96% bug free is not a good system. Preferable would be a more linear relationship: 30% perfection gets you 30% functionality, 70% perfection gets you 70% functionality, 99.9% perfection gets you 99.9% functionality. Even better is when you can front-load the system so that 50% perfection gets you 90% functionality, 70% perfection gets you 95% functionality, 99.9% perfection gets you 99.99% functionality.
How I apply this to martial arts is that if your system requires the practitioner to fully master all the subtle details at a high level in order to be effective, then your system has a problem. It takes a long time for a student to reach that level even for demonstration and much longer to be able to maintain that level under pressure. If you are using a martial art to build fighting ability, then the student should be better at fighting 3 months in than when they began, better at 6 months than at 3 months, better at 1 year than at 6 months. If they can get a 20% handle on the principles of the art, then they should be able to spar with 20% effectiveness. If they can get a 50% handle on the principles of the art, then they should be able to spar with 50% effectiveness. If the whole thing requires 90+% perfection in order to be functional, then something isn't right.