That is true, but the great majority of memory safety issues are not concurrent ones. In practice Swift and Go are huge improvements over C, C++, and Objective-C in terms of memory safety.

I'd also say they are in a reasonable space in the state of the art of safety in general. While they do not make concurrency safe and Rust does, in Rust you need to use unsafe to write things like doubly-linked lists and graphs (or resort to things like indexes-in-an-array), which you can do safely in Swift and Go. So there are interesting tradeoffs all around - our industry has not found a perfect solution here yet.