Expect an announcement posted in the next day or two.
https://flyingzumwalt.github.io/ipfs-tutorials/curriculum/fi...
It's possible but far from efficient. Those are the pain points where decentralisation doesn't really cut it.
I'm sure there's some blockchain based commenting thing out there... but the flat file feels so quaint. I might take a stab at this as a way to play around with IPFS.
Now that you name it, I totally forgot that Steem has a pretty good commenting system, and probably they're storing the entries on-chain. So maybe the answer is adding Graphene to the mix (Filecoin + Webtorrent + Graphene 2.0 as Blockchain-based distributed DB):
https://steemit.com/steem/@steemitblog/steem-developer-updat...