"Not everyone can design the product they want - its quite a rare skill. You get wrapped up in irrelevant features."

This skill is hard to find in a startup because founders have more technical acumen than the market. In other words founders are "power users," and most markets are not.

Also, editing your own work, as in looking at something that you've spent months on, saying, "this sucks," and restarting takes a lot of discipline. For a start-up that is worried about its runway, the stress of doing so can be overwhelming.