"Freestanding winter/summit tent" was probably not the best way to describe this tent, I am not trying to suggest that it can be used in the winter or on summits without the guy ropes.
My understanding is that if you have a strong pole structure that is self supporting and the panels are tight, then the guy ropes are really only doing one job, acting against wind loads. Some tents require a high degree of tension in the guy ropes to be pitched right, even before taking wind loads into account, so there may be more strain in their guy ropes/stakes, all other things being equal.
That is the only real advantage I see to the self supporting type, you might be able to get away with less stakes in the ground, or alternatively, the stakes are less likely to get pulled under the same wind loads. Obviously this is a bit of a generalisation, as there are many other factors that determine the loads on the guy ropes/stakes in a design.