Idk, maybe W3C didn't do all they could to credit WHATWG, but I didn't interpret it that way. People actually reading HTML specs know WHATWG very well. I for one appreciated W3C's efforts to publish a versioned HTML spec which WHATWG never bothered to do. Rather, WHATWG created a self-serving, never-ending process around HTML (but mostly JavaScript APIs) that saw Opera and then MS drop out of creating browsers alltogether. What exactly is the HTML5 shield logo designed to shield against?

MS and Opera didn't drop out because WHATWG didn't create versions of the standard.

Moreover, Opera was one of the founders of WHATWG, and an evolving standard was (and is) one of the core principles of WHATWG.