The concept of "being down" doesn't really apply to protocols. IPFS/BitTorrent never being down is a bit like saying that TCP/HTTP has never been down. Individual servers/client can have connection issues, but obviously won't affect clients not connected to those, and is not because of the protocols themselves.
Not to state the obvious, but... if a big centralized company built a Cloudflare for IPFS to make it easy for the masses to adopt, that company could go down just as easy as Cloudflare.
How so? Somebody links to a webpage, decentralized resolver converts it to an IPFS hash, which the client queries for any providers of that hash, and retrieves directly from them. No central authority necessary
