No one was calm? So you're telling me that everyone should be calm? The fight over if it wasnt for Zoro? You are proven wrong on panel. Luffy warned everyone first, that was the cause of Zoro being able to react and block in the first place. Killer said they couldnt dodge, but everyone shocked face was not a comparison of powerlevel to Zoro, he himself said they would be wiped out, that statement included himself. So Zoro offered himself to block thus being prepared to sacrifice himself.
The others responded accordingly and dodge from that path. Zoro block the portion/fraction he can, and Law teleported Zoro after 1 second / 1 moment block.
You said i downplay Hakai? Not at all, Zoro's feat in blocking it and sacrificing himself was great. But you are the one overestimating that feat and said "if its not for Zoro, no one would be left". You are wrong. Luffy was sure to be safe himself since he saw that from a mile away, he was shocked to see the scale of attack but also Zoro sacrificing himself.
Law can teleport so it's no problem for him at all, but theres no surprise if he's shocked as well. Again, its not a sign that Zoro is above the others, its just Oda's way to portray that Hakai is powerful.
But no, Zoro only blocked a fraction that went his way, not the whole energy. Also, Kaidou was factually playing around before Luffy so your argument about Kaidou being serious in Hakai is directly contradicted by Kaidou's own statement.
The rest is BM. Again, if you say BM was serious in Hakai, then its okay. But then, it also means that BM was serious in slashing Kidd with a named attack, only to find that Kidd has enough durability to tank it even when his head was targeted. Kidd also clashed against BM no problem in a direct contact. While in comparison, Zoro never once even tried to slash directly against BM and just chose to slash Prometheus. Putting it this way, i can even argue that Kidd's durability is way above Zoro since he dared to clash and tank BM's slashes directly compared to Zoro who was out with broken bones after being attacked indirectly.
But to respect Zoro, i wont argue that way. I just cant think that receiving a portion of Hakai (an indirect attack) is much stronger, thats if any, than clashing directly against either Kaidou or BM. And yeah its not the entire Hakai since Zoro only blocked a portion and theres an excess of energy spreading at Zoro's sides.