"User privacy should be of utmost importance for all GNU/Linux distros."

Why? It's a feature which takes a large amount of work to implement, has a series of poor tradeoffs, won't actually increase the size of the user base much, is incredibly hard to do well and is very hard to market to users. Not to mention the fact that a large number of GNU/Linux distros are aimed at markets where such user land improvements are largely immaterial (e.g. on servers).

The simple fact is that most users don't care about privacy in the same sense that DDG cares about privacy. If they did, then there would be a huge economic incentive for everyone to make these sorts of changes.