A strategic brand answers three things: what you promise, who you promise it to, and why they should pick you over the alternative. When the answers exist in writing, everything that comes after — site, ads, content — costs less and converts better, because it isn't reinvented every time.
When they don't exist, exactly what you see everywhere happens: each channel sells something different. The ad promises speed, the site promises quality, Instagram promises friendliness. None of it is wrong. Together, though, they don't add up to a single idea anybody could remember a week later.