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.