The benefit is that the markup is semantic! When you use <choices> or <choicetables>, the machine (and the writer!) understands explicitly if we are talking about:

1. <choices> where the customer has reached a decision point and must choose one of the options (such as,  take Route 66 to Boston or Route 81 to Ithaca).
   or
2. <choicetable> — where the customer has different options to get to the same result (such as CTRL+S or File > Save).

Using <ol> or <ul> eliminates semantic markup! Using <choices> or <choicetables> explicitly indicates the kind of juncture the reader has reached — and forces the writer to state if no matter what the choice, the end result will be the same (<choicetable>), or if the choice selected will lead to a different outcome (<choices>).