For the whole history of democratic primaries, the nominee was always the one that received the most votes. It probably of doesn't have to be, but it always is.
"they" in question are people of America who know more than nothing about how democracy in their country works.
Progressives are going to bitch and moan about how nobody does what they want, but will refuse to participate in the very process designed to ask them what they want.
It's almost like some idiots on the internet don't want change, they want to be oppressed.
There is a very lovely pattern I see. Every time there is a conversation on the internet, everyone totally always voted and participated and canvassed and run and also fed the homeless at the same time, and every time there are any elections upcomming, there is no end to the constant anti-democracy messages about how voting is pointless and nobody should do that because both sides.
In the end, around 20% of registered voters are voting in democratic primaries, and I repeat my thesis, every time the nominee was the person who got the most votes, every time. So the answer to your question - they already care what you think, and if more people were agreeing with you, then maybe they would do what you want. So far they're doing what majority of voters wants, and that's not on the shadowy democratic demons, it's on majority.