>> proper blog needs to have native comments
That is the most complicated part of a blog system to implement and also the one that is least compatible with a flat-file system.
The only high-volume flat-file system I know of is WMW, but I don't think anyone would design something like that today. And WMW had a lot of limitations due to the decision to implement it as flat-file.
And frankly, I'm less and less sold on the value of comments for blogs. For some topics it's great. But for many topics, it's not just spam, it's also trolls and such. I think the blogosphere was most healthy when a post would elicit a response post and that would get linked back on the original blog as a pingback... unfortunately those nine days of glory before people figured out pingback spam were short lived.
