This is it. I'm a hardcore engineer at heart who has a lot of these sales, marketing, and product folks as friends, and can attest to the fact that they also have constraints.

The whole world runs on deadlines and timelines. Even a president is elected for a specific duration. If you're in a B2B setting, the customer demands (sometimes even contractually binding) at least the Quarter when something will be delivered.

Time is the only common denominator by which different activities can be coordinated. Without some heed to time, there will be no coherence.

Presidents are technically timeboxed, at least in the US.