Saying "I found this article in EBSCO" is like saying "I made this file with Microsoft". Both statements are true, but not a lot of help in finding the right program to open the file, or the right database to locate the citation.
EBSCOHost and ProQuest aren't databases. They're companies or vendors that host databases. Lots of databases. Their logos appear prominently on the web pages, but knowing which company (or vendor) you used doesn't really help when you're trying to retrace your search results.
The same situation applies to Thomson Reuters, Springer, Wiley, etc.