I think George should have written a few simpler novels to practice good writing before he went and did a big project like this.

Guy's been writing professionally since 1970; his first full length novel was punished in 1976; he had been awarded two Hugo awards, six Locus awards, two Nebula awards, a Bram Stoker award, a World Fantasy award, and a couple Emmys before he even published A Game of Thrones.

Him having no experience writing shorter works is extremely evidently not the problem.

Him not having written something on the scale of A Song of Ice and Fire before, and writing himself into a gordian knot of plotlines and characters his aged brain might not be able to untangle, on the other hand, might.

Or he simply lost interest and would rather write about gridiron in his not a blog. 🤷‍♂️