Well the reason for the ZenBook tag is because there's a MacBook tag, but I'm not sure of the validity of that.
The MacBook tag is useful because MacBooks are "special": they have special firmware, special BIOSes, and exclusive hardware. Because of that, they generally need different instructions to get working.
ZenBooks are really nice laptops, but they're not "special" in the same sense MacBooks are. The BIOS is probably by PHOENIX, the firmware is normal UEFI, and you'd probably find much of the same hardware in a Dell or HP.
For most questions, the ZenBook is the same as any other PC. Slightly different hardware, sure, but installation instructions for a Dell Latitude E6430 should apply to the ZenBook UX501VW. Macs just don't follow that pattern, annoyingly.
Now, it can be argued that MacBook is fairly specific. Why have it when we could have just Mac? Well, this is my argument for that. The MacBook is really three separate products: Pro, Air, and the recently revived normal version. Each of these lines has its own generations. The ZenBook has plenty of laptops that take its name, but I see only two separate lines, if they can even be separated as such (clamshell and convertible). They're just models under the same product line.
Maybe asus-laptop would work, but that could just be replaced with asus and laptop used in the same question.
OK, so we do have other specific tags, like dell-mini-9 and dell-mini-10, but I wasn't around when those were created, so there's not much I can say against those, as I don't know the reasoning. This discussion is also about the ZenBook tag, not Dell.
My opinion on that tag is "no." Sure it's useful for intense indexing, but the reason for it just doesn't make sense. And if we follow the reasoning that because one model has a tag, this one should too, we'd have so many tags that almost every question would have its own.
MacBooks belong in a separate area, because they're weird to troubleshoot and use on Ubuntu. MacBooks are also really popular, so it's nice to have them organized like that. ZenBooks aren't so popular, so there are fewer questions we have to keep track of, and I think just the asus tag is enough.
I did see that there are also tags for the Pro and Air, but again, MacBooks are really popular, and it's nice to have such a proprietary device tagged as such. ZenBooks just aren't as popular. A search for "zenbook" yields 255 results. A search for MacBook yields 3,053, which is quite a bit more.
Conclusion (hopefully?): MacBooks have a tag, and that tag is useful because of their popularity; it's good for organization. At this point, I don't think ZenBooks have enough questions to merit a specific tag.
And I do want to repeat. I know there are specific tags with fewer matches than zenbook. I wasn't there to argue against them, so I'm not going to. However, I am here to argue against the ZenBook tag, so I'm doing just that.