Beaming is also caused by larger surfaces emitting a sound. Which is the case with a 7" and about 3.5kHz crossover which might be the sweet spot of this specific box.That is not correct. Beaming/lobing are created when two spatially separated sound sources emit the same frequency, which cause interference patterns depending on the angle and related path differences related to the wavelengths (interference patterns).
On the way to infinit steep you got more and more phase shift with a crossover, which leads to more nulls. The crossover region is at a smaller frequency range which is a plus.Thus at an infinite steep slope there would be no such lobing, so similar to a coincident driver.
Yes I can, because you also have to look at the properties of the drivers. There are two effects which will help that the theoretical result that you linked aren't accurate for a real speaker. 1. beaming of the woofer in the higher frequencies 2. the raw driver drop off of the tweeter and the woofer.Also you cannot assume a higher crossover frequency when we are talking about the influence of crossover steepness on the horizontal and vertical steepness.
But even in this case the reality usually shows significantly more problems at loudspeakers with shallower crossover slopes, just exemplary, a 5" B&W
vs a 5" Revel
There a pros an cons here the revel performs worse if you have a look at the total energy, since is heavily focused at 3kHz while with the B&W it all evens out. If you optimize the whole system Not only the coverage of the good looking vertical beam is important also the angles where the floor and ceiling reflection is happening are important. All in all it is not fair to say the B&W performs worse. The strength of both speakers isn't the vertical performance, as it isn't with almost any usual speaker.