I believe it isn't Donald Trump who is crashing through the guard rails. It just seems like that because people everywhere have become accustomed to liberal elites who have held power so long that they became inward looking and stopped listening to the people. It is to be expected that leaders reflect the needs and wants of the people  - that is what democracy is about. But for too long leaders have entrenched into their idealogy and ignored real people. Donald Trump reflects the peoples frustration at that and it is time people stopped calling him "off the rails"
I also agree with DieterHH's comment below about the media. The media is fighting for it's life, scrambling with screaming headlines for a share of a smaller and smaller pie - thse who pay any attention to it