Voters are ignorant, not impotent.
They just don't care enough to stay informed with their other life responsibilities and/or pleasures. The dangers of slow strangulation in the form of bills like Republicare is something they simply don't care enough to track. It'll be fully felt around 2021-2022 and by the time people realize its a problem the Republicans will have control of the government for 6-8 years.
If people genuinely cared the prescription is still rather simple:
A) Organize voting blocs to end careers on the issue of gerrymandering to prevent statehouse control == Congress control.
B) Organize voting blocs to end the careers of anyone who lowers services below Obama-era levels.
C) Organize voting blocs to end the careers of anyone who violates Constitutional liberties.
I don't think reasonable people really want people in power who are willing to do those things, they just don't care enough to do anything about it.