It is quite discouraging to see things here and there being abandoned.
Quick git blame: linked example was written SIX YEARS ago, note about it being not implemented - THREE YEARS ago. Does no one care that language reference contains examples that are not actually valid?
Another quick git blame: spec of property functions was documented SEVEN YEARS ago, warning about it being reviewed and discouraged to use - FOUR YEARS ago. It takes quite too long to start and finish the review process that way, don't you think?
https://github.com/dlang/DIPs/blob/master/DIPs/accepted/DIP1014.md (accepted in 2018, has no implementation mark)
https://github.com/dlang/DIPs/blob/master/DIPs/accepted/DIP1030.md (accepted in 2020, has no implementation mark)
...and some newer that probably can be in works.
What is the point of accepting proposals if they stay non-implemented for years?
It can also go further to things like
std.experimental.logger being "experimental" for 7 years now but I believe it has something to do with "phobos v2" and stuff.