None of those are facts. Because something is not spelled out does not mean it is not possible. They wrote up those rules to allow players to choose those options if they have a concept, but in no way does it constrain DMs from allowing such things if they so choose to do so. I think that is what some PF2 players/DMs at the moment seem to be focusing on when nowhere does it say that is the only way to accomplish those tasks.
I'm not the DM. I'm a player. So, yes, I am constrained by the rules as written unless the DM chooses to modify them.
Moreover, the structure of skills and skill feats gives you an idea of how the designer intended them to be use. Each skill sets out actions you can take by using that skill. Some are further gated by proficiency. Skill feats either provides a slight benefit to an action you could do, or allows you to use a different skill to perform an action.
By implication, if a skill feat allows you to do something, you cannot do that if you don't have that skill feat. Otherwise, that skill feat is useless. By looking at the published skill feats, you can also get an idea of what sorts of things are considered by the designers to be worth a skill feat. "Natural Medicine" allows you to use Nature instead of Medicine for the Treat Wounds action? OK, the value of that change is worth one skill feat (see Bargain Hunter, Courtly Graces, Lie to Me and Impressive Performance).
Making an impression in dealing with a group doesn't require the feat save if the player wishes to tell the DM he is doing this for some purposeful tactic that he dreams up rather than a situation the DM sets up. It puts more player agency options for the player, while not limiting the DM.
Group Impression (requires Trained in Diplomacy) - When you Make an Impression, you can compare your Diplomacy check result to the Will DCs of two targets instead of one. It's possible to get a different degree of success for each target. The number of targets increases to four if you're an Expert, 10 if you're a Master, and 25 if you're Legendary.
Heal spells remove the Wounded condition after a player has been healed to full for 10 minutes without using treat wounds, but not if the player is still wounded.
My point was that the distinction between Treat Wounds and healing magic was arbitrary. From a design perspective, it appears that the rule was included to prevent pop-up healing. From an in-game perspective, no justification is given as to why being healed to full hp does not affect your Wounded status unless you take 10 minutes.
The wizard feat allows you to do this for any spell and is a metamagic feat which involves completely manipulating the magic itself, which not every caster can do. It does not involve say using a Charm spell and not getting noticed, which a DM could allow if he wishes and is even an inherent part of the spell.
A DM
could decide that any spellcaster can Conceal their Spellcasting by making a Deception + a Sleight of Hand check. Of course, there would be no need for a Conceal Spell in those cases, so the implication by the designers is that unless you take the Conceal Spell feat, your spellcasting is visible.
BTW, you are wrong about Charm. Charm always has visible effect: on a success, the target still sees the spell but thinks that your spell was something harmless (and not trying to influence them). Plus, in all cases, the effects of the Charm spell are visible to other people present.
Why can't you use Performance to create a distraction? Does it specifically state you can't?
Create a Distraction is a Deception(Charisma) check. The book indicates (again, see Bargain Hunter, Courtly Graces, Lie to Me and Impressive Performance), that using Performance to Create a Distraction costs a skill feat.
This is something I don't get. Nowhere in the PF2 rules does it state this is the only way to do a thing nor does it greatly constrain the DM more than 5E or any version of the game ever. Unless you have players rules lawyering you, then I don't see the problem. If some player asked me if he could use Performance to create a distraction and conveyed to me how he would make it work, I would let him do it.
I have not read in PF2 where it says "This is the only way to do this." Most of the combat rules are there to provide balance. But that starting point of balance doesn't make it so a DM can't let someone do something in a different way. And if a player wanted to do it that way all the time, I'd literally write them a Skill Feat for it. Which this framework fits just fine. For example, if a player said, "Hey I want to use Performance for Creating a Distraction all the time instead of Deception." I'd say ok, "Write me up a skill feat and I'll let you take it." If they just want to do it on occasion when it fits, then I would allow that as well.
Why would the player take the skill feat if you allow them to use Performance to Create a Distraction when it was relevant to do so? Why would a player attempt to use Performance to Create a Distraction in situations where it
wasn't relevant to do so?
You seem to be running the skill feats in the same manner that I would if I were DMing PF2. Of course, as I DM, I don't really
need Make a Request actions, or Make an Impression actions, or Create a Diversion actions, and skill feats that allow you to substitute Society for Diplomacy in Making an Impression. You could rip those skill feats out of the game, but even before that, the CRB skill feats include a bunch of skills that aren't really supported by skill feats, and taking out those skill feats makes things worse.