Perhaps that article should go further? XMP is needed for sharing metadata with other apps, but I sometimes wish that Lightroom had simply moved on from XMP and not led people to think it's of great value in a LR workflow.
So much Lightroom work is left out of XMP that I'd contend the backup value of XMP is second rate. It's certainly no good backing up XMP files on their own. You'd lose stacks, virtual copies, history, pick flags, your smart and dumb collection organisation, all your work on books, slideshows, web galleries, saved print collections. You'd lose published collections, and any settings inside your keywords (eg do not export). That's usually a lot of lost work.
On the other hand, you do have to back up the catalogue. And if you do just this, and don't even bother with XMP, 100% of your LR work is safeguarded.
PS For those who do believe in XMP files, one problem with saving VCs as snapshots is that you can only do so one file at a time. Look up the Snapshotter plug-in which lets you save multiple VCs.
+1. Actually, the xmp is included in the lr database as a (readable) blob.
So i do not care at all about having xmp sidecars.