EbscoHost and ProQuest aren't databases. They're companies that host databases. Lots of databases. Their logos appear prominently on the web pages, but knowing which vendor you used doesn't really help narrow the options if you're trying to retrace your search results.
The same situation applies to Thomson Reuters, Springer, Wiley, etc. Saying "I found this article in ProQuest" is like saying "I made this file with Microsoft"—it's true, but not a lot of help in finding the right program to open the file.