It's simply business. If people use likes as a proxy to mean quality or happiness about a product then fake likes can be used as a way to bypass those hard to achieve items so that others will buy a product.

That they won't be happy afterwards is the depressing bit. It's like spam, as long as the cost of the spam is substantially lower than the profits on even a single sale it is worth it.

A perfect illustration of "what gets measured, gets done".

Or, "Once a measure becomes a target, it ceases to be a good measure."