There are other factors too.
Artists can't draw everything equally well (it may Seem that way but it isn't) or may not be able to in a timely manner.
So an alternative approach, sometimes, isn't flexing creative muscle: it's simply coping with the workload. https://twitter.com/GailSimone/status/1245715300282073090

In the example of Caesar's army encampment of 50000 soldiers drawn from an aerial view-- an artist could lose 3 or 4 days on that panel alone. It's a deadline killer.
As a comic artist I'm going to think of an alternative solution.

Prose used to support comic art. In a Roman encampment, narration along the lines of:

Banners flutter, warhorses whinny, wagons creak, arms and armor clatter, men mutter, laugh, and curse. The sound of the encampment rises and falls like the breath of a great, noisome beast.

It added another dimension to a comic page. And freed the artist from providing the entire sensory experience; which comics may need, they're still, silent images after all.

There are no rules. Because one scene may be movie-like, dialogue only, doesn't mean that must apply to every page.

When comics were aimed at ages 10-20, those readers read more prose in an issue than comics written for 21 to 70 year olds.

I'm not pining for the writing in comics in my childhood. Frankly, it wasn't very good.
But somewhere in the 80s to early 00s comic-makers managed a very strong balance between words & images.
A balance between how much prose would enhance--and how much would hamper a story.