Comment by rented_mule

It's subtle, but I think the use of "senior" rather than "Senior" in the article is an attempt to distinguish the concept of being a senior engineer from the title of Senior Engineer. The article is focused on actually being senior, not playing title games. I'd take it further and use the term "leader" instead of "senior engineer".

Leaders reduce ambiguity, so others can operate with more clarity. The ambiguity involved can be in many different domains. It can be focused on product and tech, as in the article. Another example is ambiguity around people and organizational structure, which is more common in management roles, where some in management are more effective leaders than others. It can be around finding ways for people to understand why they might want a product, which is more common in sales and marketing roles. And so on.