Some time ago we decided to do an experiment an give donors 100% control of their donation credits, and not automatically apply any of it to the site.
When you activate your credits the site recommends you consider giving 50% of your donation to the site account, but it's no longer mandatory.
Enough people give enough to the site that we decided to stick with this method. It means that while we strongly ask for you to give some of your donations to the site, you are free to make a donation and give all of your credits to dc members whose work you want to support.
In fact, this change was especially motivated by people like you who might make a repeat donation to the site specifically because they want to support members on the site individually

(note that the reason you go $26.61 in credits instead of $28 is because paypal takes their cut off the top).