You got that exactly right. The reason 3rd parties never (except Ross Perot’s reform party) get traction is because they usually rise up due to some lacking in the political system. But once they rise far enough, one of the major parties co-opts their idea and the third party withers away.
Ironically, Trump is running from a major party on a similar plank that catapulted Perot. Trade, immigration, and general disregard by the political class for the people. This time though he is inside a major party not a 3rd party outsider. And the fact that neither of the two parties have co-opted his planks speaks volumes about how captured the political class is. They can’t hear a sound unless it is spoken to them by a lobbyist with a check. They only see the world through the realm of politics, and this is why they can never reduce or reform government because all their solutions come from people with huge vested interests in the status quo - lobbyists, advocacy groups, cabinet ministers, bureaucratic chiefs and so on. Ask the director of the FDA or EPA or NEA or HUD or HHS what the problem is their answer will be give me more money to hire more regulators and pass more laws for my new regulators to enforce.
The GOP was swept into power in 2010 having lost the Senate and the House in 2008, promising to repeal Obamacare and shrink government. They even won a Senate seat from MA - Kennedy’s seat! That should have shown them the depth of anger among the people. What did the GOP to do reward the voters? Not a damn thing! All they had to do was send Obama a bill, any bill, reflecting the desires of the voters. Yes he would have vetoed it but at least they could say they tried. They did not try. A few ‘renegades’ pushed the budget talks to brinkmanship against the wishes of the elite. They were ostracized for it. But then a funny thing happened in the primaries, when all of a sudden we had 4 outsiders in the top 4 positions. At one point Trump, Carson, Cruz and Fiorina combined had around 65% support of the voters, 3 of them never held elected office and Cruz a novice “renegade”. Jeb with $150 Million to spend did not earn even 1 single delegate! You would think they would learn from all this. But they cannot learn, they are captured by the system and think all ills can be solved by more regulation and higher budgets. They just don’t get it. They never will. They have to be replaced.
Wow! That is a money quote right there!