There are some very knowledgeable people here in the forums like let's say
@hkrommel and we can always rely on them to educate us
I appreciate the compliment and will get to the argument itself shortly. First, to those who are commonly on these forums it's probably apparent that I've stepped away for a while, and I probably will do so again after this post. While I genuinely enjoyed the discussions I've had here, it just got exhausting between the tankies, wehraboos, and assorted moteley crew. Too many times I would spend hours tracking down sources and piecing together a detailed defense/attack of a particular position, only to have the other poster completely ignore/disregard everything I said in favor of some simplistic narrative. Some posts on this thread are a perfect example of this sort of thinking. That, RL pressures, and my diminishing interest in the game all gave me a great excuse to step away. All that to say that I probably won't be substantively involved after this post.
To the part of the discussion you pointed to, I think you're correct. IIRC the part of Dunkirk the Allies controlled didn't have port facilities, and even if it did the Luftwaffe's dominance of the skies would render that a moot point. Therefore the Allied forces in the pocket, even if they
could break out, could not be sufficiently supplied to really go anywhere or do any real damage. They'd only succeed in wasting their limited supplies and strength to achieve...what exactly? I think the Allies and Germans were on the same page here. The force at Dunkirk could be safely ignored. It was doomed to surrender unless some miracle happened. That's why it's the "Miracle at Dunkirk."
The Germans also probably knew that the British were already assembling other BEF forces and that the French weren't out of the fight yet. They probably didn't know exactly how weak the Allies were after these events. Besides, it's a basic principle that you bring as much strength as is prudent to every fight, which in turn minimizes your own losses and maximizes the enemy's losses. So wasting that strength to force doomed soldiers at Dunkirk to surrender rather than using it to force the French out of the war would be foolish. The French were a
far bigger threat.
As for whether the Germans taking out the Dunkirk pocket would have changed anything, I think not. Would it weaken the British? Absolutely. But the British already had their minds made up, to the point where civilians would go into the line of fire to rescue those soldiers at Dunkirk. There's nothing the Germans would realistically offer the British to make the British actually agree to a treaty. Further, the British had more than sufficient force to stop Sealion. It's worth noting that the British didn't know that at the time, because opponents in war don't generally share this kind of information, but with hindsight we know that Sealion was impossible. Even if you could magically teleport the Italian Navy to German-controlled ports, and combine it with what was left of the Kriegsmarine after Weserubung, that would be a laughable force to throw against the Home Fleet (and that's ignoring that the British could simply relocate their Mediterranean fleet, and they wouldn't have to teleport). In the air, anyone who has done their research knows that the British were extremely unlikely to lose the Battle of Britain. The Luftwaffe
never recovered from the mauling it took, particularly the losses of experienced pilots. Really, the Battle of Britain was to the Luftwaffe what the first months of Barbarossa were to the Wehrmacht: a gutting of the experienced soldiers/pilots and officers alike.