This is a quick answer from the top of my head: Various other projects have implemented threshold ECDSA as well, but to the best of my knowledge, all of them have some shortcomings in properties that make the resulting system problematic for real-world use. And I recall to have seen a couple of exploits, at least one at the protocol level where the private key could be reconstructed after a (rather small) number of computed signatures, of threshold ECDSA implementations as well.
One notable project that has implemented threshold ECDSA is ThorChain. From what I remember, their approach for threshold signing assumes that network communication is synchronous and that the protocol stops working when one node stops working, while our scheme relies on asynchronous networks and degrades gracefully (up until some point, of course) when nodes stop working.
(see also here: https://www.reddit.com/r/dfinity/comments/tr6wic/what_is_the_difference_between_canister_ecdsa_and/)
@victorshoup, the inventor of our threshold ECDSA protocol, can definitely give some further details on this question.