I've attended a few singles socials recently wherein people were assigned different kinds of foods to bring. This was done alphabetically; for example, people whose last names start with the letters A to L might be asked to bring a side dish, whereas people with names from M to S might be asked to bring desserts and T to Z would be asked to bring drinks.
What typically happens, however, is that there is an overabundance of cupcakes and cookies. Is it because there's a disproportionately large number of people whose names fell into the corresponding range? I seriously doubt it. What happens -- and of this, I'm absolutely convinced -- is that a lot of people just decide to bring a bag of cookies regardless of what their surname initial is. After all, it's simpler and easier to do that.
In most cases -- and again, I feel confident in saying this -- it's also lazy and inconsiderate. I don't want to judge any individual on this matter, as I'm sure that some people were legitimately pressed for time. Knowing human nature though, I don't doubt that many people simply decided to take the easy approach.
Is it disastrous? Not really, but it does create obvious problems.