A nicely written piece, and as an employee I can appreciate it. However, as a manager I feel this is a biased and grossly simplified and naive view. Managers, as do their employees, deal with complex business circumstances. Unlike their employees, managers often also deal with complex interpersonal and sensitive private situations. The complexity in a manager's job role has more facets than their employees, and a good manager shields their employees from much of this where possible and necessary..

Performance assessment is difficult, especially when companies require relative assessment amongst peers. Employees have a naive view of their own individual performance, but little perspective relative to the performance of their peers (especially when those peers are in different levels with different scopes).

Everyone wants to be told they are doing well. Many do not like to hear about areas in which they can improve. Often the "surprise" as you put it comes down to a lack of awareness of peer's contributions or areas for improvement, or from a level of self-delusion around scope, contribution, effectiveness, impact, value or other measures of performance.

It is easy to call the manager's "3 paragraphs" as a "pathetic piece of paper" but bear in mind some managers may be doing this for 15, 20 or more staff, on time budgets that are already stretched, while continuing to effectively hold down the fort on all the "normal" day to day work such as HR, personnel, customers, finance, business compliance, organisational politics, and others. My personal view is that the comments on the piece of paper are for the most part written by the employee and the more important piece of the puzzle is, as you say, the conversation during which the employee hopefully gains some perspective on their relative contribution and insight into the future and areas for improvement.

Let's see you try writing a similar piece from the other perspective - can you?