I think I understand both viewpoints: it is indeed not feasible to fake it before you make it in case of Dropbox. However, if you are offering automated reports

I think I understand both viewpoints: it is indeed not feasible to fake it before you make it in case of Dropbox. However, if you are offering automated reports once a week, there is no problem putting together an HTML template, some excel sheet and an email script where a person does the work for a few pilot customers. So I think when you mentioned "particularly novel or value-generating product" you meant that the idea scores close to 0 on a "fake it before you make it" scale? Is there even such a scale? Barrier of entry is closest I can think of.