I don't understand the point at all. If you need to add some condition later on, why not just add it then? What benefit is there to just marking out the spot where you might add the condition at some point in the future?
I've also seen it in code with iterative adds, for example:
for crit in criteria:
sql += " AND " + crit
As you develop and are constantly creating / debugging queries where you often add new and or or clauses as a whole line, that becomes much faster to add and remove those same lines as they're a single shortcut away in nearly all text editors.