Why has mongorestore stopped recognizing the --ssl option
The instructions for installing on OS X manually via curl currently use the non-SSL version as an example and do not actually link to the latest version (eg. 3.4.2 is included at the moment but 3.4.4 is the latest production release). I've raised DOCS-10176 to correct this information.

In the interim, if you visit the MongoDB Download Center which is referenced directly above the curl step you can find links for of the available packages to download. The OS X downloads for MongoDB 3.0+ should all default to a version with SSL support, or explicitly highlight if a selected distribution does not include SSL encryption.