Since the wording is identical, I assume this description reflects that "Genealogy & Family History" is a re-start of the earlier effort, "Genealogy." The latter was closed not too long before the re-start effort began. Here's the link to that closed proposal:
Why the word serious? I can only guess that the author of the original proposal was hoping to be inclusive in describing the target audience.
How simple, straight forward and inclusive can we make new proposal description?
How about I propose the description that follows, then you and others can suggest ways to improve it?
"Q&A site for those interested and/or engaged in the practice or hobby of Genealogy and Family History."
"Q&A site for those of all skill sets and experience levels interested and/or engaged in the practice or hobby of Genealogy and Family History."