Communication skill is a supreme skill for any person. It is like a server without the network drivers which still has network interface controller but not using it efficiently.
Communication allows us to achieve our goals, to ask for something, to make sure other person understood what we really wanted to say and it is not so easy.
Moreover, communication allows us to go outside of human designed systems which might have "bugs". For example, you are in cafe which offers you a a lunch with coffee or tea for 5$. You can ask for water instead of tea or coffee but if you are hesitated to do so you are limited to the system itself always.
For most developers it doesn't mean you should be an expert, but you should be able just to talk, to tell your arguments to other team members and managers, to ask for help, opinion.
For sr. engineers and especially for engineering managers, tech leads, architects, CTOs communication is a critical skill.