Honestly, you're right. No one believes in the manga, it's fan fiction now a days anytime it comes down to Hashirama.
That is the thing, when it comes to Sasuke, any excuse can be used to hammer his feats and it is considered valid by default. But when it comes to characters like Hashirama and Naruto, anything can be fished out of ones posterior to say that it's legitimate.
That was Enton and unfocused flames, both of which are weaker than a Focused Amaterasu.
Sasuke's Amaterasu after all, managed to completely melt through and shatter Kaguya's ice which is something RSM Naruto was unable to do.
As for the topic, Amaterasu is the highest level of Katon and it should burn through Hashirama's Mokuton, esp. when the flames are manipulated to pierce through it.
Finally, someone who actually reads the manga without looking at images' surface value nonsense. People so easily forget that Amaterasu burned through the chakra Kaguya had used to create the ice-block to save herself from sealing. It's proven by the manga and the databook that she uses her own chakra to manipulate and create dimensions (gravity manipulation should be the final nail in any naysayer's coffin).
TSBs utterly failed. They were moving like snails, unable to trudge through the chakra and Ice. Enton melt them like butter. To think that Hashirama's wood even stands a slight chance is beyond preposterous.
lel i guess we arent reading the same thing, naruto could touch them and sasuke could see them but couldnt touch them.
Ah, so that's why Sasuke's attack connected. Since he cannot touch them, I mean.