It isn’t just a question of minority rights, but also, monority opinion on any issue. Reading about the policies implemented in some states and communities, like local school boards, dissenters would naturally advocate for the federal government to step in.

The dissenters should advocate for redress of their grievances ONLY if there is a question of constitutionality, which is what the judicial branch addresses. You can’t actually believe that a minority that opposes constitutionally valid policies that were determined by the majority of their community should petition for those policies to be overturned by the federal legislative branch, simply because they can find majorities in other locales who agree with them??

However, the huge disadvantage of federalism is that it can result in a distortion of equal chances for all citizen. Just look at the wide range of moneys spend per capita on school education in the states. Noone can deny that the youth of, say, Louisiana, on average gets a worse education than kids from New England states. Regarding the huge impact of qualification in one’s carreer, the odds are against children living in poor states. This is shameful, and imho violates the principle of the constitution. That’s where federalism should have limits, and where there should be national legislation equalizing the differences.

I’m all for meeting national needs with national legislation. But in cases where the way forward is not clear, federalism allows for a great diversity of ideas to be tried and for the results of those different approaches to be evaluated. That seems like a very powerful tool to me.