I'm glad that you didn't have bad experiences with Kovid Goyal but others weren't so lucky.

I didn't mention that I also don't need to use Calibre as I can load my epubs onto the device via wireless connection.

I also don't use Amazon's ereader software so that I'm able to read epubs without converting them and also having an UI interface on the Kindle that suits my habits better than the official one.

For these reasons I don't have a need for Calibre in the first place.