The original (Shaftesbury) "Combination" ladder was designed by window cleaners for window cleaners back in the days when there was no 'Elf 'n' Safety' and they all had to know what they were doing and looked out for each other. The Shaftesbury ladder was designed to be used in just about any situation a window cleaner would come up against. A standard parallel ladder will only be stable if all four ends are in contact with the ground and the building. This is impossible to achieve in many situations.
The 'pointer' ladder was designed to be perfectly safe in 99.9% of situations. Anyone with a basic knowledge of geometry will tell you that any three points always lie in the same plane, in other words when you set a 'pointer' both feet and the top will be in contact with the ground/wall and it will not 'rock'. The reason the 'pointer' has splayed feet is to overcome the fact that the top is too narrow to prevent the ladder turning sideways so the bottom is made much wider to increase the stability.
Thes ladders are the safest you can use for window cleaning IF YOU KNOW HOW TO USE THEM. The problem is most window cleaners these days come into the trade with little or no training from people who know what they're doing
Regardless of what today's Elf and Safety "experts" may tell you, these ladders were designed to be used in complete safety without the need for them to be anchored/tied or stood on 'stoppers' or other 'ladder stabilising devices'.
WHY WOULD YOU USE A LADDER THAT IS INTENDED FOR PAINTERS/BUILDERS ETC, WHO WILL SPEND A LONG TIME AT EACH POSITION AND WHICH IS NOT SUITABLE FOR A TRADE THAT REQUIRES FREQUENT MOVES ON UNEVEN GROUND WHEN THE IDEAL TOOL IS THERE FOR THE ASKING?
All you need is a few hours training from someone who was trained by real 'old time' experts and has spent a lifetime running up and down 'pointers' :

Incidentally: the 'pointer' is more properly called the 'tree bottomed point' and was a development of the orchard ladders used by fruit pickers. There are some pointed ladders on the market which do not have splayed feet. NEVER USE ONE OF THESE, they are dangerous, will twist unless you keep all of yourself between the styles and ought to be banned.