What proof do we have in favor of the use of CSE encryption

Thank you, I start understanding.
Have you heard about gp4win http://www.gpg4win.org/ , using the open source PGP Methods… Which benefits are there using CSE instead ?
Many people say (and their argumantation is good !!) that security critical software should be “open source” , like gpg4win so everybody can check the program code !!!

Especially interesting is this one:
“The private key that’s used to create each S/MIME certificate is not sent to the CA and so there’s nothing to hack that would endanger certificate owners.”

This of course is good. But wait a second, is the private key not assigned by the CA being the primary hierarchical institution ? Then the key is there as well, isnt it !?

Another issue:

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This means that still in that scenario the message gets to be “sent” to your Servers…hence a potential attack site for hackers as many people might be using and reading many of their these e mails on your servers…

Thank you