The first paragraph has been adequately responded to.
In the end, if you removed all description from the mechanics the game would literally be this:
I roll 23 to hit.
The enemy rolls 26. You miss.
He rolls 26 to hit.
I roll 24. He hits and does damage.
The fact that one of those is Spiderman is completely impossible to tell from the rules. There might be movement going on but there are no rules for how often or how far you can move or a limit to the number of times you can move so you don't have to engage the mechanics at all for these things.
Contrast that to a system where the mechanics are more connected to the story and you get something like:
I stick him to the ground if he can't get out of the way, DC 23.
He rolls a 21 and is stuck.
He spends his round attempting to get out. He makes a 22 on his strength roll. He manages to break free.
I spend my move action to climb up then swing over to other side of the street.
It's impossible to remove the description from the second example entirely because the mechanics ARE the description.
Your first example with minor changes sounds just like typical D&D combat without mentioning the damage numbers. The second, with minor changes, could be from either system. These example prove nothing because you're choosing to make them unequivalent. Namely, you're choosing to ignore the character sheet descriptors for first, but not for the second (presumably D&D):
I roll 23 to hit.
AC 26. You miss.
He rolls 26 to hit.
AC 24. He hits and does damage.
I'm gonna try to pin him with webbing... 23 with a d10 effect die.
He rolls a 21 and is immobilized.
He spends his round attempting to get out. He makes a 22 with a d12 effect die!
I got a 19, he breaks out. I'm going to use Wall Crawling and a Swingline to put myself "Up a few stories and out of reach"...16 with a d8 effect die.
Doom Pool rolls an 8, so you make it.
And that second example skips how the players would need to build dice pools using their players traits. For example, when pinning the enemy Spiderman's character might say "I'm going to try to pin him with webbing so that's d8 Solo, d8 Weapon for the webs with a bonus d6 and step up the effect die from my webbing's
Grapple SFX, and I'm a Combat Expert d8. What the heck, I'll say 'Welcome to my parlor, Mr. Fly.' to get another d8 from my Wisecracker distinction."
Note that he
might say that. If you're building your dice pool directly
in front the other players at a table, you probably don't need to announce every little thing. You could just collect your dice and roll. If someone challenged "where'd you get a d10 effect die?" you'd explain it "my SFX with webbing" just like in D&D you might answer a "why are you rolling d12 damage" with "my weapon does d12 vs Large creatures."
The real difference here is that MHRP (like FATE and many other modern rpgs) has a universal method for handling complications to the standard attrition of combat points. These rules almost universally rely to some extent on the common sensibilities of the players to adjudicate. D&D still has multitudinous factors and minor rules to handle all of these things individually and explicitly.
That is certainly debatable. Both the way I read the rules and watching the people play on YouTube, the point of having multiple powers in each category(some of which are just plain worse than others) is that sometimes you won't be able to use one based on the current fiction. For instance, Spiderman might have his webshooters taken away or have his hands tied and pointed in the wrong direction so he can't use them. Sometimes there might not be enough room to properly use super agility.
During these circumstances the DM can say "No, you can't use that power right now". I rather got the impression that each time you activated a power you should really check with the DM to determine if it's possible.
Plus, there's some wiggle room in powers that aren't described in a lot of detail where the DM might simply say "No, The Wolverine IS the best at what he does. But what he does is NOT the dishes. You can't use that here."
Most of the Youtube videos I've seen seem to be people learning or trying out the system. Often, it seems to my eyes, that they are confirming how the rules work, rather than getting permission from the GM. Additionally, the medium requires a slowing of play. Of course, I would expect folks, even in person, to check with their fellows and make sure that they aren't being jerks when they are unsure of their thinking. That happens in almost every game I've every played, even some board games! I will say that I haven't been able to play as much MHRP as I'd like, but I'd imagine this speeds up quite a bit when the players are as familiar with each other and the system as they are in the typical D&D group (if there is such a thing.)
The other two points don't make much sense to me. If an enemy disarms your D&D character, does that imply that you need to check with the DM for permission to use your other weapon/ability? Doesn't it just make sense that you'd need to take action to respond to that? Is a rule that states the exact details of what it means to be disarmed actually needed or helpful? The last point just sounds like a player who either doesn't understand the character or is just being contrary. I'm confident that we all are familiar with players who try to weasel things out of their character abilities regardless of system.
To be connected, the mechanics have to describe what is happening and the story has to describe the mechanics.
I don't feel the story itself has any onus to describe the mechanics. The players may need to adjust the narrative to reflect mechanical results...which can be good and bad, heaven knows HP have created their share of narrative nonsense. If the narrative is constantly strained by having to adjust to nonsensical results of the mechanics or narrative sensibilities regularly causes the mechanics to be ignored, then the mechanics are the issue.
RPG Mechanics very rarely actually describe what is happening in a story sense, especially given your requirements of doing so after removing any descriptors attached to the mechanics in question. Take conditions in 4e. They may describe mechanically to how the minis are allowed to move or how the controllers of those minis must adjust future rolls, but
they have no explicit connection to the story side and cannot. Such descriptors are left to the players, and are essentially irrelevant to the numbers. Is the figure slowed because you have injured its ankle, hit it with some kind of cold spell, or entangled it in vines...dunno unless you know the player's description of the power that was used
when it was used. That connection is no different from getting a complication in MHRP, with the exceptions that the effects of the complication are
only meaningful in the context of the narrative (there is no such thing as a "blank" or "undescribed" d10 complication) and a clever player might turn a complication into a bonus for an action for a Plot Point. (I'm "covered in ice" d8? Great! I'm gonna use the ice slide down the slope like an otter and try to hit those goons like ninepins.)
Beyond that, the only substantial difference between the MHRP and D&D mechanics I detect is that the D&D mechanics can also be viewed in a "story-free" way as only modifying abstract numbers and movement of pieces on a game board (with varying success dependent on edition). I do not find that property a sufficient justification to claim that they are therefore better connected to story or narrative than MHRP's mechanics.