I've seen a similar situation play out at a startup and I can see your point. However, I think there's a difference between talking to potential customers about requirements they have vs. promising to deliver a solution for them on the spot.

IMO you don't have to, or rather shouldn't, close the sale when first reaching out to potential customers like this. The goal should be to simply validate the problem statement - if that's done with enough potential customers you should move on to the next part of planning and building the initial implementation.

To your point, new information might still surface at this point, which could lead to the project being dropped. Having not sold (promised a solution) to anyone at this point, the likelihood of unhappy clients is rather low.

All that said, I think calling this initial work "sales" might give the wrong impression here, as I would categorise it more as market research. Whoever is carrying this work out should be very aware of this and not actually close the sale on something they are uncertain can be delivered in a profitable manner.