Because it is ambiguous goal which under any reasonable interpretation has massive consequences and major unintended side-effects. My favorite sport is basketball. What is the 'equality of outcome' in the context of the NBA? Is it that players are evenly distributed across gender lines? Across economic lines? Across national lines? Across racial or ethnic or religious lines? In our society, it would probably be understood that NBA should be proportionally represented by each identity group. So you should see 70% white players, 15% hispanic players, 12% black players, 5% asian players. Is that the right solution? But is the fact that black Americans dominate the league actually a problem? And what the heck are you supposed to do to fix it?

The other point is that in a free society, you cannot guarantee equality of outcome because people are going to make personal choices that will be magnified and influenced by whatever sub-culture they are immersed in. Professional basketball in the early days was over-represented by Jews, because it just so happened that interest in the game went viral in that sub-culture.

Tech has an over-representation of men because it grew out of a particular nerd sub-culture. There's nothing wrong with doing outreach to get non-traditional sub-groups developing an interest in programming, just like there's nothing wrong with the NBA running clinics in China to get Chinese kids into basketball. But it's not racism that the demographics are the way they are! In a free society you should expect that!