The Skype desktop software and web interface will receive the update treatment soon to match the Android, iOS, and UWP applications. When this happens, the legacy feature to sign in using your Skype account will disappear so any accounts set up this way will need to be merged with a Microsoft Account before the update.
https://www.notebookcheck.net/Microsoft-will-remove-option-to-sign-in-to-Skype-using-Facebook-account.266984.0.html
Because of the microsoft account, or whatever they changed it to after buying skype, is the sole reason, i do not use that bloatware anymore.