There was no such implication. You're misinterpreting a conditional as a biconditional.
I think action play, in my case, lends itself to solo play. I don't think the camera mode matters. I don't think the third-person camera would be mandatory - in fact, I still might not like that as much as the tactical view. But if I didn't get to give orders while paused, I wouldn't want there to to be a party.
I do think action play discourages full use of the party. In fact, I would argue that action play inhibits full use of the party, as there will necessarily be characters who are, as time passes, acting without your direct control.
But the camera mode should be irrelevant.
...I was under the impression (again it would appear) that your statement about solo play and action play was a declarative, an abstract statement defining action play and solo play. I didn't realize you were talking about yourself in particular (making a subjective quantification).
Though for the sake of the argument, 3rd person camera is much closer to the action and potentially allows one to recognize an enemy action (and thus make a counter-action) quicker than the iso-cam.
I personally don't place any real value on a party or lack of a party in relation to action play (outside of the fact that they're generally incompetent). And as far as "full use of the party," if "full use of the party" means that the player must control them, then A) you're right, and B. the tactics/AI system was abysmally designed. A game like Final Fantasy XIII (I recognize you'll not have played it, but it's simply a reference) is designed around non-controllable party members than actually have excellent AI.
i'm not so sure about that. I'm trying to imagine if anyone could beat a game like Baldurs gate 2 with the use of a different camera than the one that BG2 used (on any difficulty level). If you don't see everything that's going around you how can you react if you want to have full control over your party?
edit: and here we go again camera/difficulty, is there a relation? 
Is it possible to pause literally every second (heck, every fourth of a second) in BG2?
If so, then the game can be paused, the camera rotated, and threats dealt with.
Though from your description, it sounds like encounters in BG were terribly designed where enemies would spawn behind you as well as in front of you. Is that true? Because, amusingly, in DA ][ I could play most of the game (most definitely if playing as a mage) focusing on threats at the edge of their little "circle," and thus keep all enemies in sight.
Oh no, what I mean is as it stands nightmare has been fun. I'm a bit fuzzy in my definition of fun, and obviously it's subjective, but call it sufficiently challenging that I will be using reload, but not so hard that I'm slaving over a spreadsheet to min max my build/gear. I'm just not sure how you maintain a challenge for a decent group while keeping things solo friendly. I suppose level based encounters will help, you can always head in when you've got a couple of levels on the mobs. I don't know if that applies to all encounters though.
Well that challenge is maintained by the existence of such options as Nightmare. They can design Nightmare for total control of a full party, and not really worry about solo-ers complaining about difficulty--it's Nightmare, after all.