Interesting from a technical perspective but with native RDP clients readily available on just about every platform, I don't see the need for it.
Browsers are sandboxes, your native client often isn't, there is definitely a huge advantage, portability and embeddability as well, it's also simpler to sniff traffic (and MITM it).
Not many good MFA options for native RDP/RDG. Putting it in the browser lets you wrap the whole thing with OAUTH/passkeys etc
When it’s in a browser you don’t need to install anything on the local machine. I used to use Apache guacamole to access my machine at home from work when I was stuck in a cube all day.
https://guacamole.apache.org/