Perhaps that is true, but you can't deny that it makes sense. Take this exact ball for example. That team had no real star players to speak of except maybe Gaylord Perry. Perry is an easy signature though, worth very little. Of the signatures I can make out from that scan, there are a couple of deceased players, who are also not tough (Todd Cruz and Al Cowens). I think I see Riche Zisk. He is tough, but not impossible, not overly expensive. There may be a couple of other not so easy signatures as well. Overall, it is a fine Mariner ball for those who like/appreciate the Mariners, but nothing close in value like a newer ball that might contain Griffey, Arod or Ichiro.
Now, take the time to practice all of those signatures to the point of perfecting them enough so as to possibly fool most buyers. Now spend the time signing a ball. Use different ink to "throw off the experts". Wow, you just made $30! Hardly the kind of return a scammer is looking to make for his time invested. He'd rather fake Mantle, Maris, DiMaggio or Williams at $200-300+ a pop.
When I am doing my research on those $1 autographs, I have often been fooled into thinking they are safe because they are so cheap and common, they couldn't possibly be fake.