The big trend now seems to be state governments blocking public policy innovation from cities. The first time this came to my attention was with states blocking cities from deploying municipal WiFi a few years ago, in order to protect incumbent broadband providers. The current example is the "bathroom laws" in NC, MS, and SC, which block municipal ordinances extending legal protections to LGBT individuals, and furthermore block cities from guaranteeing any civil rights that are not guaranteed by the state.
In the first case, the cause is probably just that it's more cost-effective to lobby at the state level than to lobby every city council. In the second, it seems to be that the state legislatures are controlled by their rural counties. Both of these are probably problems with state constitutions, and so, very hard but not necessarily impossible to fix.