I think it’s because most often advocates are not promoting a specific methodology but a broad set of possible electoral reforms. Even people who study this in depth (like the article author) get substantially different results based on what they value and measure, and by methodology. That’s not something a civics class is going to address for people who want more fair choice at the ballot box but can’t possibly know the outcome of one approach or another without seeing it in situ.
Edit: I’m saying this from the perspective of someone who’s spent a lot of time reading on the subject and wouldn’t dare pick a favorite for my country (US) or locality. I just want the opportunity to try systems that are likely more fair.
This is one of the great aspects of states (localities in general) mostly governing themselves even in important things like voting. Some state tries something new, and everyone observes and can learn from the results.
If all of the new things states are trying were concentrated in just one state the churn would destabilize it too much. By spreading out the chaos we collectively get to try many new things at once, but avoid being overwhelmed since each locality is dealing with fewer new things.
One major drawback is that efficiencies of scale can’t be taken advantage of and inequities at scale are easier to propagate. So we have a very slow process that ends up disenfranchising a larger amount of people than I’d be comfortable with in a modern developed democracy. This is extremely evident when you start comparing how well governments run in other Western democracies.
I meant to respond to GP earlier and you got to it before me admirably, but if I may be more terse: some of these states are still experimenting with rehabilitating the Confederacy.
Edit: I’m saying this from the perspective of someone who’s spent a lot of time reading on the subject and wouldn’t dare pick a favorite for my country (US) or locality. I just want the opportunity to try systems that are likely more fair.