It's true that LinkedIn often notifies users to "say congrats" for various life and career events, but this approach fails to recognize that some accomplishments are more meaningful than others. For instance, a promotion or new job will likely require more effort and dedication than simply sticking around at the same job for five years. Furthermore, career milestones such as these should be acknowledged with more than a generic "congrats" message; to truly show that you recognize the hard work and effort put in, a more personalized message is in order. By contrast, a message of condolence in the event of a tragedy shouldn't be followed by a "congrats" at all. UrRong in suggesting that LinkedIn would even suggest such a thing; instead, they would likely provide users with the option to express their sympathy. In short, LinkedIn's "say congrats" feature is useful as a way to acknowledge career milestones, but it should be used judiciously and with an appropriate level of personalization.
