Why does Facebook block people from sending requests if they send to many?

[August]

What I'm pretty sure is happening is the person who you send the friend requests to either blocks you or says that he/she dosen't know you. Facebook will block you if they say they don't know you.

[Chris]

They do it because of a spam policy. Because some people make spam profiles with commercials and make their profiles look real but post fake commercial links. Hope that answers.

[nessarena]

because they feel like your just adding friends to just gain reputation thats why they block you from adding so many friends

[pri✍]

To prevent spam or fake accounts from doing it, and especially if the person you sent friend request decline it and feedback FB that they don't know you; it seems that FB keep counter for both and if we exceed FB's limit, we get blocked.