Not necessarily. There are social environments where things aren't said directly, but rather communicated through choice of words, body language and actions. People can make their thoughts abundantly clear without saying them directly, and some would expect you to understand even if they don't communicate it directly.
Figuring out if a person/group says things directly or indirectly is part of the code. It's not necessarily about insecurity. Even a person secure in their own abilities can benefit from understanding when people communicate heavily between the lines.
"That's stupid" is referring to something being stupid, not someone. You need to invent additional context to interpret this differently.
What I meant is that people don't only ever say you're stupid by super-directly saying "you're stupid". "That's stupid" is not a big leap. Yes, context is key to interpretation.
To say something is "stupid" is to say that's it's the product of unintelligent thinking. Somebody calling my idea "stupid" may not be saying that I'm universally stupid, but they're at least saying that I was momentarily stupid to suggest that idea. Same thing if you call my idea "retarded" or "idiotic", or conversely, "smart" or "clever".
The argument could be made that we should all be rational beings of pure logic, incapable of taking personal offense or being emotionally slighted or discouraged by such judgements. But we're not. And if we were, we would also be capable of limiting our output to objective conclusions such as "that won't work" rather than subjective judgements such as "it was foolish to suggest that it could".
Which is exactly why it is fine to call an idea stupid. Everyone knows that people are fallible, so they know that your idea can be stupid without you being stupid. You taking that personally is stupid though, as it implies you think it is possible to be infallible.
- That's stupid
It's clearly talking about the idea. No one says "That's X" when referring to someone. When someone shows me a painting and I say "That's beautiful", I'm obviously referring to the painting, right?
No, but I think the choice of adjective is important. Suppose instead of saying "That's a beautiful painting" I said "That's a masterful painting".
The sentence structure is the same. The adjective is still modifying "painting". I'm still saying the painting is good. But the word I chose more directly implies a judgement of the artist: I am describing the painting as the product of a master painter.
I get the same impression from hearing "stupid idea". Stupid is a description of intelligence, thinking ability, aptitude: attributes which lie with the idea's originator, not with the idea itself.
Similarly, if you come up with an idea and someone tells you it's stupid, you might conclude (especially if it's a recurring pattern) that they don't think you are very smart. If that is not the conclusion they wanted you to come to, it is on them for not communicating better
Saying that a particular painting is bad does not imply that everything that person has painted is bad.
Nobody is grinding away at anything, perhaps other than yourself. It seems many people here are mystified by your unyielding interpretation of a two word sentence and nobody can seem to get a straight answer out of you, other than repeating the truism that "it's not obvious".