I agree with both of you, and I most definitely appreciate the support you give; not just to me when it's been needed, but for others as well.
People asking for support should always reply back; not just to give thanks, but also to help others who can benefit from the result, be it successful, or not.
Having stated the obvious, I think it can be helpful to understand why this happens.
I think many people are afraid to be chided or
"attacked" for trying to get help to problems they're not able to solve on their own. Not so much here anymore, but trying to get support can be a rude awakening in a support forum, especially when there's such a difference in the level of knowledge between those asking for support, and those giving it.
So generally speaking, if a person is bold enough to ask for help, it's not uncommon for them to suddenly disappear after that help is given.
They want to get out when they're still alive!

This is just a weird part of human nature, but from my perspective, it's also understandable.
For the help and support I'm able to give, I just give it because it makes me feel good. So I'm already ahead of the game even if nobody cares to acknowledge it.