A. Most cordless phones don't use Lithium Ion batteries. They use nickel-based ones, which should be charged for an extended period.
B. So the company who makes Seido batteries tells you the same bollocks that Seido does. Can't imagine why that is!
C. You said it was an article, not some words from you.
D. When the phone says it's fully charged, it's not the battery saying that. The battery only reports its current mV. The OS has to make that distinction, not the battery. If the battery was saying it was charged when it was not, it wouldn't charge because the circuits would refuse to charge. You can't force-charge these batteries (without blowing them up or damaging the circuits, at least).
E. I have an EVO, and having a Seido battery isn't really relevant to the conversation. Of course, having an EVO isn't truly relevant either, since the facts don't change whether I have one or not.