Sure, this is not the optimal way to pitch to a manager. But why wouldn't the manager be able to point out it isn't a good idea _without discouraging the pitcher_? Why not start / continue the conversation by responding with a question — "Sounds awesome, what would be the benefits short term?" ... "And how about the long term?" ... "Do you also see downsides?".

Sounds like the discouraging part in the articles' examples is mostly the about the manager failing to rigorously communicate about the "management-internal" conversation that leads to rejection...