Apart from their physical appeal, it's believed that the systems are simply becoming a more viable solution for standard desktop users. AIO computers typically use components designed for mobile computers and are commonly underpowered compared to full-fledged desktops.
However, mobile processors are increasingly powerful and prove sufficient for basic family or corporate usage. DisplaySearch notes that while AIOs have historically been benchmarked against traditional desktops, they are gradually becoming a market of their own.
Apple holds a majority of the market, which isn't a surprise considering the iMac's popularity. HP trails in a distant second, while Acer, MSI, Sony, Lenovo, Dell, Fujitsu, NEC, Asus and others are all on the map with shares from largest to smallest in order of mention.