Wouldn't this be sticking it to the company though? Wasted unproductive phone calls hurt the bottom line and produce no sales, and as you mentioned the employees running this scam get bonuses, so costs go up.

What could be better to hurt the company than that?

In other words, the goal here is to disincentize spammy calls from businesses.

Causing telemarketing to be less profitable and more costly is a good way to achieve that, so this tool being used by "both sides" is a good thing.