Even if that's true, you are developing for one platform so the comparison is a bit disingenuous. Mobile development is made slower because of fragmentation, not the tools. Unless you've magically found a way to port your apps over to Android and Windows Mobile..
Windows Mobile is a bit player still, doesn't matter for startups (or non-startups).
That leaves you with Android and iOS. Most startups can start with iOS and add Android later -- there just aren't the sales numbers to prioritize Android development.
So we're back down to one platform, with native development providing definitively better results with less time.
Supporting differing platforms is not ideal, but somehow we built the entire PC industry on top of this concept, and it worked out. Maybe we should be looking at ways to bring ObjC code bases over to Android, or something that would let us re-use non-UI code.
