Wow, that's harsh - and maybe not the best way to get info.
Echoing what most of the above posts have stated above, I've found Calibre to be incredibly flexible. By design, from what I can see.
Since it's open source, it's as flexible as you're willing to make the effort to make it.
I was impressed enough to contribute to Calibre. And, I'm a cheap wad by nature
- if I was willing to voluntarily contribute $ to a free software, at least I've put my money where my opinion is.
to kovidgoyal and everyone else who's added plug-ins, comments (constructive), assistance, and enhancements.