people of action don’t participate

Are you claiming that activists don't vote? Or that being an activist isn't participating in the democratic process?

I'd like a source if you meant the former and seriously question your idea of democracy if youmeant the latter.

Voter participation is shockingly low for a supposedly “free” population.

I'd claim that this is the output for a system which alienates so much of the people's power in everyday concern. Not the reason why the system does that.

it does a whole lot more than screaming from the rooftops about how much of a fool other people are for actually participating.

1. Protesting is an important part of any democratic process. That's why freedom of speech is so paramount in (supposed) democracies.
2. This depends on your perspective. If the system does work in your favour, you might be right. If the system doesn't work in your favour, then agitating against it imho is more productive than participating.

Consider the french revolution. Was agitation against the aristrocracy more effective than praying and being sure that the people above did what was best for their country?