This is not an excuse. Just the reality because it's not as straight forward.
People take martial arts for many different reason so when you say Experts, who are you referring to?
If the Kung Fu teacher is an expert in kung fu forms, then I don't automatically expect him to be an expert in fighting. Just because he trains and studies kung fu doesn't mean that he knows it. It also doesn't mean that he techniques aren't valid. It just means that this specific teacher doesn't know how to use them because his expertise is in forms. So for me. I don't expect someone to know which techniques create the best result or how to win the fight. If I learn from them, then I will not be learning how to fight or use techniques from them. If they are really good with making martial arts forms look good, then my best route may be to use those martial arts to be an action actor or stunt double. Bruce Lee is a good example of how martial arts makes a movie fighting scenes more exciting. No real fighting experience is needed.
Then you have experts who know how to use martial arts techniques. These guys are the ones you want to learn from if you want to learn how to fight using martial arts techniques.
You also have martial arts experts who only care about fitness. Billy Blanks is a good example of that. He used to compete, but no he just does it for fitness.
You may look at this guy and call him a fake martial arts person. But he has applicable skills. He just chooses to focus on fitness. Which probably made him richer than many UFC fighters. Google says his net worth is $20 million.
If a martial arts expert claims to be able to fight using his technique, then he should be knowledgeable in that area. If a martial arts expert doesn't claim to be able to fight using the techniques, then that's ok too. Because he's being honest about his knowledge and what his knowledge consists of.