It emphasizes time measurement (track how much time you're spending actually doing the work) rather than time management (plan when you intend to do the work).
I think the measurement focus is useful as you will naturally react to the measurement and that will affect your behaviour.
But planning when you intend to do the work also means planning what you will do in what sequence (i.e. prioritization), and taking into account external constraints.
And those things are absolutely essential when you constantly have more things to do than you can finish in one day, and with interdependencies on other people's work.
Preferring "actually doing the work" on stuff that is easy to finish because that is encouraged by your measurement could be quite disasteous，if it causes you to delay more important things, or to fail to address things that block other people.
I think the measurement focus is useful as you will naturally react to the measurement and that will affect your behaviour.