Because selecting candidates based on tech stack is almost universally the sign of incompetent tech management. Anybody who understands software, knows that intelligence and master of fundamentals trumps tech stack experience without exception. Linus Torvalds would unquestionably become a better Ruby on Rails developer within four weeks than 90% of people with 10 YoE in it.
Good organizations hire talented and bright people with mastery of CS and SWE fundamentals. Bad organizations think "oh we use Java, better hire Java programmers". Really bad organizations think "oh we use JUnit, Spring Boot and IntelliJ, better hire people with experience in JUnit, Spring Boot and IntelliJ"
One of the strongest signals of how good an engineering organization or a tech team is how few specific technologies they list in their job ads.
Good organizations hire talented and bright people with mastery of CS and SWE fundamentals. Bad organizations think "oh we use Java, better hire Java programmers". Really bad organizations think "oh we use JUnit, Spring Boot and IntelliJ, better hire people with experience in JUnit, Spring Boot and IntelliJ"
One of the strongest signals of how good an engineering organization or a tech team is how few specific technologies they list in their job ads.