This tag is for questions about the history of programming and computing. A measure of demonstrated research is expected for questions with this tag.
The general answer to all questions about "why was this language feature not implemented" is that the team who designed the language decided that the benefit didn't outweigh the cost.
Cost can take many forms. It takes time and effort to implement a language feature, but there is also the intrinsic cost of complexity: does the feature make the language more complex or ambiguous, out of proportion to its potential benefit?
Beyond demonstrating more than a modicum of research, good historical questions will also highlight how the benefit of the language feature appears to outweigh the cost.