C++ before 2011 springs to mind. From "Direction for ISO C++"[1]:
"C++ is expert-friendly, but it cannot be just expert-friendly without losing important streams of new talent. This was the case before C++11 and C++11 reversed that negative
trend."
[1]: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p200...