Spam isn't just about email anymore!
Spam used to be the problem of email. It was the unsolicited and unwanted commercial messages from people you didn't know and with whom you had never had a business relationship. Now the concept of spam has expanded to include social media and can also include someone messaging you out of the blue with the only desire to send you a link to a website.
No one likes to receive spam, whatever its source or purpose. People who send it earn a bad reputation. The idea behind social media is to make connections with people you know or through people you know. Commercial messages are deemed acceptable if they are given in the context of receiving some other information or some other benefit, but seen as unseemly if given solely to sell them something. On many social media platforms, sending them is a quick ticket to being unfriended or unfollowed.