That's not what I said. What I said was "I'm not saying that every existing language has solved it". TypeScript, C#, Kotlin, Dart are all examples of popular languages that have solved this problem.
Another problem that's currently being solved is the inability to do basic data modeling. In particular, the inability to say "it's A or B". That has been solved in some languages for a long time but is now solved in a number of popular languages too.
There really have been quite a number of advancements in the last 22 years, but sometimes it feels like it's just the bare minimum (ex. being able to do basic data modeling, not having everything be surprise null, etc.). It does seem like it takes a long time for good ideas to propagate into the languages that most people are using. The field is young and it's going to take time for things to mature.
The next big thing is going to be effect/capability systems (tracking which functions do I/O, access the filesystem, etc.). That might take another 22 years to go mainstream, but that doesn't mean progress isn't being made, it just means that we need more new languages that try new things, evaluate new concepts, and establish techniques to be adopted by other languages.
