I've never use codeacademy, but with exercism and the like the exercises are all very much "puzzles" rather than actual software engineering challenges. I want to see database problems, architectural questions, networking, reverse engineering, security concepts, API authoring, etc.
So as you describe, they're not great for starting out with programming, and for advanced programmers, string manipulation exercises just don't teach you anything.
There are plenty of video courses, stuff on Udemy teaching you databases, etc.
I think it's an untapped market for the webbased coding challenges, although quite hard to pull off if you are needing to have a database for the users to interact with, etc. The same would apply for any network-based challenge, or ones requiring interacting with an API, etc.
If you've ever played with HackTheBox / TryHackMe (hacking playground) they provide VPN config details where you connect and can access all sorts of services, DBs etc to hack.
I imagine a similar solution could work for coding, networking etc training.
So as you describe, they're not great for starting out with programming, and for advanced programmers, string manipulation exercises just don't teach you anything.