In this fast paced world, specialists are required to get the job done accurately and efficiently. Therefore, it is must to hire Individual contributors who are specialists in their domains through the long experience they hold in their domain. 

Individual Contributors love autonomy in their work, therefore strongly dislikes a manager who's a micro-manager chasing status on every single item and arranging meetings day long which are highly unproductive to ICs. 

For the performance evaluation of ICs, it is important that is done by the direct stakeholders and not the mediator in between who has hired the IC on behalf of the stakeholder/ client as mediators rarely have insight on the performance of the IC employee and would randomly appraise the employee without knowing how their performance been in the period i.e. how much % of jobs were completed and how many remarkable achievements they have earned - an insight which only direct stakeholders know about and is often missed while communicating to the appraisal decision makers.

Also, whenever the IC employee chooses to leave the firm, the stakeholder/ client won't have any power/ control on exploring the ways to retain the candidate and the mediator won't know if the employee must be retained or should let go as employees are considered to be dispensible and replaceable easily.