You should. I was under the apparently mistaken impression that people who get into YC at least have a functioning demo, and generally have users already. So when my friend and I were applying, we limited ourselves to ideas for which we could create a semi-functional demo in the few weeks before the application deadline. We ended up getting rejected because of the idea that we chose, and rightly so, but I wonder what ideas we would have come up with if we had not felt so time constrained. (I am glad that we were rejected because I don't think that we were ready to start a company yet, but I am curious anyway.)
please do. in the last few years, the model for seed funding seems to have moved largely to having an mvp, if for no other reason than demonstrating technical ability.
maybe i will write a blog post about this.