> A better alternative to "you have to sugarcoat all your thoughts by 30% before you speak them out" would be to train people to be better at taking criticism

The amount of extra effort involved in having a few people "sugarcoat" (as you call it) is tiny compared to the effort in retraining vast swathes of people out of what is after all a fairly standard human behaviour. Behaviour so standard in fact that this doesn't count as "sugarcoating" at all, really, at least not in my view - more like the process of actually assembling a persuasive argument from the unrefined raw material.

(I originally started this post with "Come on, come on, don't be silly". But then I took it out, because it felt a bit rude. But, if you don't think it will hurt, you can imagine I left it in.)