[giantg2]

It's because schools teach to the market. How many schools teach COBOL? There are still companies that want to hire COBOL resources, but most schools aren't going to teaching because the market is too small. It's the same for query optimizers and compilers, only even more pronounced by their very nature - these are things that a very small number of people create because you want a standard or consistent experience with this level of tool. It's like my cryptography course - I'll never use it because the best practice is to use the industry standards.

Another reason you don't find many people with this experience is that there aren't many jobs for it. Going back to my cryptography class example, if I don't have the need to use the info after taking the class, then I'm not going to remember it.

That said, there should be plenty of candidates who are willing and capable to learn this stuff if companies would actually train people.