Like for example one problem with the 2 "partial poles" would be that to make that an actual solid directly, that one single surface would need to have an edge that was joined to its own self (to the same surface I mean). The surface joining mechanism is not expecting to see that kind of a self edge join except for the regular "seam" edges on a closed surface.

Also with Loft having points stack right on top of each other will sometimes cause the loft to be a bit unpredictable right in that collapsed area, like you may get some very little bulges and things like that which will be hard to see, particularly if the points are separated by even a tiny amount instead of 100% unified into one location.

By giving just even a small amount of clearance space it is going to avoid these kinds of problems.

- Michael