The trick is to hang around other people with the same sort of mindset. Growth-mindset people constantly make this error with fixed-mindset people, and alienate potential allies in the process. (Indeed, learning not to do this could be an important area for growth.) Fixed-mindset people tend not to make this particular error as much, because most people shy away from people who constantly make them feel bad. In the process they develop a sort of confirmation bias for their fixed mindset, though, because they don't come in contact with anyone who could point out where they might grow.
Concur. Whenever a reader points out an error in my blog — whether of fact or attribution or spelling or grammar or syntax or punctuation — I take the time to thank them and ask for more of the same. Why? It only makes my blog better. I love being corrected.
Not everyone is uncomfortable with self criticism and making mistakes, so the Golden rule isn't universally applicable here.
Some people consider forthright language to be a sign of respect. It can show confidence in the rationality, empathy, and maturity of the audience.
The problem is that it's like saying "I'm not a pessimist or an optimist, I'm a realist" - everyone says that.
I really value when people are forthright with me. I know some, I respect them, and I really value what they say, even when it's hard. OTOH, the ones most likely to claim they are ("I just tell it like it is") are also the ones most often just using it as a license to not bear any responsibility for their words.
Which doesn't mean there aren't people out there that ARE honest and clear...just that you can't trust someone claiming to be one of them to be accurate.
Now model the person as in your outgroup. Same analysis but now you feel good when they feel bad. Pointing out flaws will feel good, independent of viability of correction. A real person will be somewhere in between ingroup and outgroup, how good you feel for criticising them should tell you where.