A trending list is erased by the next one. Hugging Face’s API returns the list as it stands now and offers no way to ask what it was last Tuesday. The only way to have that record is to save it every day, which is what the collector does.
What the record lets you do
Check when a model first appeared and how long it stayed. See which papers led on the day a model was released. Compare the likes and downloads a repository had on two dates. Cite a stable address for “what was trending on that day” instead of a page that changes under you.
Two kinds of day
Days recorded by the collector hold both lists with the numbers of that day. Days before the collector started hold papers only: Hugging Face keeps its daily paper lists, so those were rebuilt after the fact and are marked as such. Vote counts on rebuilt days are the counts at the time of rebuilding.