D has been on the market for significantly longer than Rust and reached 1.0 full 8 years before Rust had a 1.0 release, so not surprising at all.

But the rate at which Rust is being adopted is much faster than that of D.

Moreover Rust brings something novel to the table and even inspiring other popular languages, like Swift, in the process.

D has nothing that I'd consider novel. So personally I'll trade D for Rust any day. Luckily, we don't have to pick.