No, you're not overreacting. It's called "vote/follow bartering", and it doesn't fly here very well. The people doing it are either new or bots. I'm betting a good blend of both. 

Sending someone an unsolicited private message with no intention of being *human* to the person you're messaging is spam. It's no different than knocking on someone's front door, making them get up out of their comfy chair, only to throw a business card in their face and run away once they open the door. 

![](https://steemitimages.com/DQmaKSjjquFRUFCKkLcZoKBt8JF4r7k6Q9UJU8jCgfkm1SX/image.png)