Semantics (meaning) tends to mean different things to different people.
The Validator provides a good test of...
1) Will my content index at all.
2) Will my content index as I imagine it will index.
If the Validator produces many errors + warnings, especially of certain types, then it's unlikely you'll achieve any SEO traction.
So the syntax you list is valid, thus will likely index sensibly... and... best to think like Bots think...
Keeping in mind Bots are dead simple.
If I didn't care about SEO, I'd ignore the issue completely.
If I did care about SEO, I'd use li + ul, as the semantics (meaning) of this approach tends to correctly index with Bots (like GoogleBot).
New/Improved ideas about how to design content are great + may or may not index correctly.
The real question is "Will the dead stupid GoogleBot understand what I'm cramming down it's craw."