When we hear we don't need deadlines; we don't need estimates; we can slice work small enough to have each and every activity be the same size, with no variance; we can use small samples with ±30% variance to forecast future outcomes in the absence of any uncertainties; we're Bad at Estimates; and the plethora of other reasons for not doing the work needed to be proper stewards of our customer's money - we're really saying we weren't paying attention in the High School Statistics Class.
All project activities are probabilistic, driven by the underlying uncertainties of the individual random processes. When coupled together - only trivial projects have independent work activities - cost, schedule, and technical activities drive each other in non-linear, non-deterministic ways. Managing in the presence of this uncertainty means risk reduction work or margin. Both are needed.
When it's not our money, we are obligated to be stewards of the money from those paying for the production of the value. This is a core principle of all business operations.
The notion that those on the cost side of the balance sheet have an equal voice of those on the revenue side when it comes to managing the firm's money to produce products or services seems to be lost on those not accountable for managing the money.