People who have good ideas and want to implement them and even run for office exist, today. But politics is a difficult game to win when you make more enemies than allies.
Also, the more immediate and impactful reform you advocate for, the less likely any of it is to succeed as it would take increasingly more money and labor to do. Even China does reforms as part of a 5 year plan. Even if, for example, the USA's DNC got the reigns to start reforms like transitioning to green energy, codifying bodily autonomy in the constitution, and passing Universal Healthcare and Universal Basic Income: if they don't get everything they promised passed before losing their supermajority then voters will blame them for not accomplishing it.
That's why Bernie Sanders succeeded where so many have failed. He didn't fight the system, he wants to fix every individual problem with it until eventually it stops being what it is.