There are many scenarios I could posit, but I'll pick one. Let's say your pre-revenue start-up needs a product for sale within 4 months, because that's your company's runway. There's a lot of work to do and limited resources, but if you don't meet that deadline your company has no product to sell and you are out of a job. Are you really arguing that it's poor leadership to say: "we have a hard deadline- the product must be ready in 4 months"?

There are many such hard deadlines in life, and failing to recognize them and motivate your team to meet them is poor leadership.