...But your list of tasks is already endless.
All of them require your attention!
If you have little to do, it's not a problem.
However, if you're busy... this is not feasible.
Finding good people is difficult, training them is expensive.
Even if you find the perfect person... You still rely on one individual.
Don't have a marketing budget of tens of thousands per month?
Well then your account is often managed by the intern of the assistant of the assistant.
Not ideal.