I think there's a serious misunderstanding here on how beading or sheeting affects water spotting. The misunderstanding is twofold.
For one, some seem to use and understand the term "water spotting" in layman's terms, focusing on the spotting part. However, in reality it is a technical term, which is not really about the "spots" part. but refers to the process of mineral deposits being left back from water (or any other solvent for that matter) on the surface, when it's allowed to dry by air, through evaporation. The other misunderstanding is the consequence of the first, and is about how much of these deposits are left back on the surface during drying, depending on the water behavior.
Let me set these straight here!
Contrary to what some have stated, in regards to water spotting and in this (technical) sense, it doesn't really matter how quickly the water evaporates from the surface, because - as already said - water spots are caused by the minerals originally floating or solved in the water being left back on the surface - and the amount of those obviously does not depend on the speed of evaporation, or how much the water sheets or beads. It only depends how much water was left on the surface in the first place, and what amount of contaminants that water had suspended (or has collected during the drying process, which however should be in most cases negligible compared to what it originally contained, unless it was distilled prior to getting on the surface).
What might be misleading here is, that in regards of visual appearance, there's a definitive difference between water spotting depending on water behavior. if the water is lying on the surface in distinct beads, then the deposits will also form in distinct spots/circles, whereas if the water covers the surface more evenly (ie. is "sheeting"), then the deposits will be also more evenly distributed on the surface, and thus less discernible to the naked eye. However, what's important to note here is, that even in the latter case water will obviously leave back the same amount of mineral residue per volume unit. The only difference will be, that those deposits will be more evenly distributed, and because of that they will more just fog up or haze up the surface (which will be less obvious to the eye), and less prone to form distinct spots on it.
The other important thing you've to realize is, that beading and sheeting are not properties that live on their own, but direct results of water behavior on the surface. If the surface is hydrophilic, water will cling to it and spread on it (ie. it will "sheet"); and if it's hydrophobic, water will try to move away from it, and only leave tiny beads behind, that are not heavy enough to roll off (ie. it will bead). What's important here is, that obviously hydrophobicity and heavy beading allows less water be left back on the surface, which in turn will also mean less minerals to be left back, than with "sheeting".
So, even though if left to dry on its own, beads might leave back more apparent (more distinct) water spots on the surface, all in all they will still leave back less minerals (=contaminants) on the surface, than if the water would spread out (sheet). The former might be preferable in the short term because of the visual impact, but in the long term, the clear coat will fade and haze up far faster when the surface is not hydrophobic, and thus is not beading.
It's also worth nothing, that a hydrophobic (ie. heavily beading) surface it a lot easier to dry with either pressurized air or towels, than a hydrophilic one, because water will roll off a lot easier from it and there will be less water to wipe off in the first place. Because of this, hydrophobicity/beading will also help you generally leave behind even less mineral deposits, because you'll be able to clean the surface faster and more efficiently, allowing less time for those minerals to settle and bind to the surface.
So, no, contrary to what people have said here, hydrophobicity/beading is not only not pointless, but actually very preferable even in regards to avoid mineral deposits from water (aka "water spots") being left back on the paint surface. The only thing is, that if you don't or can't dry the surface properly (because for ex it's left out in the sun after a rain), these deposits will be - even though likely lower in total amount, but - more discernible to the naked eye, than they would be if the water would just spread out more evenly on the paint. In which case the contaminants would be still there, and even in larger amount - you just wouldn't be able to *spot* them, at least in the short term; but in the long term they would still do more and also more visible damage to your clear coat.
