Most probably thats the case. But I'm just wondering, is dusting attack really that effective for the attackers?
It depends on what they are trying to do. If it's to link multiple addresses to one pseudo personality, then it could be effective. If the purpose is to hack and steak funds, then dust txs doesn't offer much except suggesting that a certain group of addresses could belong to one person and gives an idea of how much bitcoins that person actually owns.
Scammers could know your identity on the forum (or in real life) and may know a couple of your addresses which may be empty or doesn't give away your actual worth; a successful dust attack could reveal that information.
but are there really victims who has been successfully scammed or hacked by these attackers? I mean I've seen people who got scammed through phishing websites, could this be connected to dusting attack?
I doubt phishing attacks could be linked to dust attacks. Your address or group of them doesn't offer enough information to support a phishing attack.