Learn English – what is the opposite of the stretch

According to the definition you cite (and my understanding), a wall of text is a solid blob of text without paragraph breaks. It is therefore hard to mentally outline a "wall of text". Your example seems to be of the "opposite of a wall of text" that you seek a word for.

Some words that might help:

• "broken up"
• "staccato"
• "disjointed"
• "not fleshed out"
• "outline"

If you need a purely technical term, you might try looking up laminar flow.

From Wikipedia:

In fluid dynamics, laminar flow (or streamline flow) occurs when a fluid flows in parallel layers, with no disruption between the layers.

P.S. I've just recalled the word unperturbed. Checking for "unperturbed stream", "unperturbed flow" on Google brings up not that many results, but let it be here, just in case.