Blue
Ravenous Bugblatter Beast of Traal
Sorry, but can you explain how characters do something without the players saying they do it?
Sure thing. characters live in the world. Therefore it is my responsibility to give the characters the information they would notice simply existing.
If I told one character "You see what look like words in some language engraved on the sealed arch" and another character "you see the sentence 'Speak Friend and Enter' in dwarven runes around the sealed arch", I am having the characters do something - experience the world - without the player having to explicitly tell me they are doing so because it's already an assumption.
By the same thing, if a player intentionally had his character lie in such a way to present it as true to the listeners, then they are using deception (charisma) even if they don't call out using the skill by name.
To be frank, this and @clearstream's examples are "I want to be able to use the mechanics to he 100% sure, with no risk, that I can treat another as if tgey are bad."
Would you be okay with an insight check that, if failed, means you must 100% and with utter, unshakable conviction believe the other character is telling the truth? No, what insight represents is a risk free check to establish the proof to treat another as a bad actor, in this case a liar. That's not interesting enough for a roll.
I'm not sure how you think any of that applies to what I've been saying.
On the other hand, players do build their characters to be better or worse at things, and taking away the player's intentions on if their character is skilled at reading people (or knowing arcana, or spotting traps, or whatever) it taking away player agency.