It was always thus. Indeed, full script was the only way comics were written until Stan Lee founded Marvel Comics. These days it's gone back to full script across the board. The "Marvel Method", as it was called, plot, pencils, script, never gets used anymore.
That's not at all true. There is not, and there never has been, just one way of creating comic books industry wide. There's no Director of Comics that declares: "Okay, everyone's writing comics full script now." The creators and editors decide on the best way that works for them for each particular project.
Alan Moore is famous for his ultra-intricate full scripts that include every possible detail, but he still encourages his artists to approach things in a different way if they have a better way to go about it. Other writers are more comfortable working what's commonly called "Marvel Style", where the the dialogue is written after the artwork is drawn to a general plot. (And BTW, Marvel Style is not only used at Marvel. It's just called "Marvel Style" because that's the way that Stan Lee's working relationships with Jack Kirby and Steve Ditko evolved in the 1960s. Kirby and Ditko were both really strong on pacing out their own stories, and as Lee was editing the entire Marvel line in the 60s, it made the most sense to him to write the final dialogue to their pencils, often adjusting plot points as he went.) With Marvel Style, you're often writing to the available space, or writing to convey plots points the art omitted, or both. And yes, lots of times, the artist might not draw what the script indicates. Most every comic book writer has horror stories about the artist not drawing something vital to their script or plot, either because it was too tough to draw, because they were on a tight deadline, because they wanted to tailor their pages to the art collectors' aftermarket, or all of the above.
When I interviewed Doug Moench around 2013, he told me that he uses a sort of hybrid method between full script and Marvel Style, where he writes a full script for the artist to work from and then revises it after the art is done to best match his dialogue to the art. Mark Evanier has said that he works a slightly different way with each one of his artistic collaborators, sometimes writing full script, sometimes doing plot first/Marvel Style, and sometimes something in between. Keith Giffen plots out his comics by drawing rough thumbnails for his artists to work from. Every single artist, writer, and editor in the business has their own preferences, and if they're at all smart, they'll tailor their approach each time to what's best for the final product.