In most cases it seems to me that the considerable research won't turn anything up. That seems especially true of the kind of bios that have turned up here. But I am thinking also of the thought that someone writes an article one some person, giving no real evidence for notability, and it's up to everyone else to dig that info up. My gut reation is, you want something in the encyclopedia, it's generally up to you to justify that when you put the article in.