Microsoft is going to prevent old versions of Skype from working. In the near future, all versions of Skype below Skype 6.13 for Windows and Skype 6.14 for OS X will be blocked. Microsoft recommends you to upgrade your Skype app to avoid issues in the future. While most users are happy using the latest version and do not remain on an older version, there are some reasons why many people stay with older versions - especially those who do not like the changes Microsoft made in newer version of Skype.
Here is why old versions of Skype are still popular:
- Aggressive in-your-face advertisements: the latest versions of Skype do not allow you to turn off ads, such as the huge top banner in the chat window or the square ad in the bottom left corner. Old versions like Skype 5.x have less obtrusive ads which can be blocked easily.
- HTML support in chat: this feature was dropped from the Skype desktop client, but with the old version you are still able to use it.
- Latest versions are very resource hungry and consume significantly higher memory and CPU than any Skype 4 or Skype 5.
- Latest version of Skype does not support some webcams which the old one handles perfectly.
- Latest version of Skype does not support/has issues with Windows XP which still has many users.
This is not even a complete list of why people wish to stay with older versions of Skype, there are some removed features and bad UI changes, but you get the idea. Microsoft will not allow you to sign in if you are using an older version of Skype - this is a repeat of the same policy they used for Windows Live Messenger in the past by forcing users to upgrade. If you depend on Skype to stay in touch with friends and family, you have no choice again.
However, you can try to avoid ads in the latest Skype using the following tutorial: How to disable ads in Skype’s chat window. Or you may consider switching to a higher quality video chat alternative such as Google Hangouts. Hangouts is not feature-rich like Skype but is extremely easy to use and contains less annoyances.