...so in summary: all you have to do to implement a basic bookmark sort is pursue some ornate, tedious work around every time you add a bookmark.
The problem is that that work around is slow, and it gets in the way (as so many other non-features in the post 12.15/17 opera tend to do). Sure the actual page access functionality has improved significantly, but the organizational features are severely lacking (see: progressive digression). So much so that this browser is actually resulting in massively reduced productivity for most skilled users who came from 12.15/17. It's kind of like how the windows CE/pocket pc platform had extremely powerful organization features (business user features [contact to calender seamlessness all wrapped in a logical layout, etc, etc, etc,]) that simply disappeared with later smartphone platforms (probably because those developing them totally forsake their original base [the business community, particularly small business users], and started instead developing for some other user base with lower standards]) such as android and windows phone [which have GUIs that look like they were developed for mentally stunted kids... think sponge bob meets interface/GUI development).