Basically what this will do is when a visitor types in a partial URL such as
www.sample.com/bluewidgets they will automatically be taken to the index.html page by default.
I don't know that it will do any real harm but I don't see it as providing any real benefit. If anything it dilutes what little strength the keywords have in the URL with "index".
Other than "hearing something" about it, was there anything the designer offered as a "plus" for structuring files in this way?
Dave