Linux doesn't have the issue with codesigning. And no evernote doesn't (it's more of a page mechanism) and yes OneNote does but OneNote one Linux is non-existent and OneNote on the web is bad.
Code signing is not an issue, it is a feature. You can think of it as a way to programmatically check that the executable has not been modified since released by the developer.
FOSS sites often recommend that a downloader check the hash of a downloaded file against one provided, never seeming to realize that if an attacker can replace a .iso file that there is a high likelihood that they can modify the MD5 hash shown to match their modified file.
