Earlier quoted context omitted.
Really? Assessing demand before diving into app development is considered a bad thing?
How is a web form going to give you any useful data about demand? There's no investment or interaction with actual users. If you want to assess demand, make a minimum viable product.
1) Get them to agree [or disagree] that the problem exists.
2) Explain your solution and get a reaction.
You should already have some idea of demand before you write a single line of code (other than the code they wrote for this simple page)