M7,
I'm sure you are correct. However, at this point I'm just too lazy. After I build the steps, I intend on leveling the ground below them and will put some gravel over the dirt to keep the framing out of puddles. Then I plan to set the steps on the gravel. I'm sure the steps will settle some but I can always tweak the ground under the steps if that happens. I don't plan on bolting the steps to the porch; they will be free-standing. If settling becomes too much of a pain, I could set the steps on some pavers to slow down the setting.
Another consideration is - we may eventually replace the steps with a ramp. If we do that, a concrete footer under the existing steps might get in the way.
Obed