I would think because IPNS is IPFS.. and you asked how IPNS compares to BitTorrent. Maybe I misunderstand your question, but the reply seems totally on topic and a valid answer to your question.
IPNS is a system that runs on top of IPFS. You do not need IPNS to use IPFS.
That's technically correct, but in practice the term "IPFS" is commonly used to refer to both ipfs and its optional feature ipns.
Not in my circles. IPFS is used a lot for storing and archiving files but IPNS is rarely used or mentioned. The only situations I've seen where IPNS would be useful, ENS was used instead as it's more reliable.