Skype isn't part of the tech startup scene either. They have not been since 2005 when ebay acquired them for two billion dollars - and now they have been resold twice. The erroneous Silicon Valley references just facilitates the misinterpretation of Skype as a startup to support the linkbait article title.
Frankly it would seem that analysis of the stock vesting expectations of hackers in Tallinn is more relevant to the story and the structure of the Silverlake partner agreement than the expectations of Silicon Valley programmers when it comes to attracting and retaining technical talent at Skype and among the people mentioned in the techpress, it has been difficult to find any in key technical roles.