Why WHATWG created a separate specification for URL standard ?

The rfc3986, by IETF and W3C, is still the internet standard for URIs, as mentioned in that website.

That also includes url and urn descriptions. Then why WHATWG had to develop an entirely new standard for URL ?

Moreover, in the WHATWG’s URL living standard, its mention in the “goal” section that – this standard obsoletes the rfc 3986 and 3987, yet according to ietf rfc 3986 is still an ” internet standard “.

This is very confusing, I believe I am not understanding a key technical aspect regarding uri or URL or standard bodies etc…

Can someone give me a cohesive, detailed explanation for the above question, with references if possible..