AbdulAlhazred
Legend
Because it literally does not contain a description of WHAT I DID. I mean, yes, as I even stated, the two may virtually become indistinguishable and interchangeable in some contexts. "I eat the pizza!" is an action declaration, but it probably also largely subsumes and implies the goal of "having the gustatory experience of pizza-eating" or maybe "having the nutritional experience of pizza-eating" (and which is the primary focus is likely abundantly apparent from context). "I try to disrupt her spell casting" is a nothing-burger as far as D&D-like systems go, it might as well not have even been uttered as it adds nothing but color to the proceeding. Now that, or the off-balance one, MAY prompt the GM, in some cases to invent an action for themselves, but that's just lazy playing! I mean, most of us probably do this kind of thing often, but its still not the full explication of what's HAPPENING. The GM is taking control of the PC and saying "Well, he's a fighter standing in front of this other guy, OK he probably shoves him..." Honestly I'm surprised this sort of thing doesn't get your hackles up, as you are IME pretty hostile to GMs filling in the blanks in other contexts.How is "I try to knock him off balance" not an action declaration? Same as "I try to disrupt her spell casting" and similar.
But the GM isn't going to 'want' such clarification, it is ABSOLUTELY VITAL to have it, because you cannot adjudicate "I want to push him over", you MUST adjudicate something like "I step forward, sword across my chest, and shove him hard!" Again, the GM can take over the PC and basically say this, or at least assume it, and proceed, perhaps. Even that won't always be possible.Sure, the DM might want clarification as to HOW you intend to try these things; but as declarations I think they stand up.
Like it or not, some players are happy to leave the "how" piece to the GM to fill in. And in other cases the how might be fairly obvious and thus not really need to be stated.
No, you may be used to making light of the process and thus obscuring the distinction, but it is a vital distinction!