Why so many restrictions on promoting in Peerfly?

You aren't allowed promote an offer this and that way, no email marketing, no forums, no links in comments.... That's plenty of restrictions. Why? If I don't spam, why not?

1) Do they really penalize those who promote using some of those methods?

2) What free methods that they allow would you suggest then?

It is not the network imposing those restrictions; it is the advertisers who make those calls.