Masocongty.vn was developed from the need of finding company. There are some formal & non-formal source that can be searched by the same way. But they cannot offer the users what they want.
The formal source just supply some criteria to search, cannot use Vietnamese without signal. I see the best reason to use this is the largest database. Besides, there are a lot of "just SEO" pages. These ones are filled with almost advertisements and some piece of information about the company. I think this is not what user wants.