Feel free to your opinion.
The calibre rationale is that people who have manually configured a conversion for a specific book, won't want to go back to the generic defaults.
I shan't argue for one side or the other.
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Email autoconversion is actually not.
It is an email. If the format desired does not exist yet, it will first trigger a conversion.
Same thing applies for Send-to-Device.
Conversions follow the normal rules of conversions. I cannot think why anyone would think otherwise.
Your Thompson quote doesn't work...