So you're telling people who want to win Dem primaries to eschew the power brokers and special interest groups and instead do something completely different than everyone who becomes a Dem nominee in every race in the country. Sure. Is the Dem party supposed to only run folks who are fabulously wealthy for county clerk on up?
There is not near enough money to put up sacrificial lambs in 80/20 Pub counties and districts. You would need money to get folks to get their brains bashed in running those races. And that's just to get them to run. Dems don't contest a bunch of races because politically-minded folks in that area either just aren't Dems or don't have time and/or money to waste for absolutely no reason. It isn't a top down executive call to not have candidates.
Let me risk being doxxed for a moment. I've run for office. I'm sure you know, but to win the primary, all that was required was winning over a majority of the 300 or so local party activists. This is true for both parties. Those activists are members of local PACs that put out mailers with recommended candidates. The 10s of 1000s of voters that show up can all be seen with these sheets, and the 1-2% that engage with campaign volunteers and candidates on their way in usually look to their sheet as the conversation unfolds. I had many say I'd won them over, but who knows. In campaigning for 9 months, I personally got the word out to maybe 1-2% of people who voted. Obviously this is not the kind of campaign for which anyone ran TV ads. Street signs, a couple billboards, and some internet ads. Beyond races where TV ads do run, the PACs basically choose the winner of the primary, and in tons or races, the primary winner of one particular party is the winner in the general.
With a shitload of money, you can overwhelm the local political "machine." That's it. I've said this before, but your proposal requires something like a 10-1 or better ratio of dollars raised and spent by Dems over Pubs.
Your proposal is akin to fans calling for a coach to call the touchdown play.