Alchemists knew that alchemists from other families had their own legacies; they would not pass down their alchemy skills to other families, let alone to an individual, unless one became their disciple or a family member.
Jiang Tang was so generous in sharing his knowledge; this was a learning opportunity for them, and perhaps he was a teacher invited by the family.
They certainly wanted to seize this great opportunity to improve their own alchemy skills.
What Jiang Tang initially thought of was to show off his Alchemy Furnace that was used to refine supreme elixirs.
But upon reflection, he realized that showcasing the Alchemy Treasure Furnace while constantly exchanging supreme elixirs would interfere with his avatar's pill refining in the space and would delay his important business of selling pills.