[Oatka]

Most likely because no politician wants a loss on their record by running in a non-winnable district.

I read that sometimes they promote a no-hoper to see what kind of money or votes he can draw. Also, it seasons the expendable Newbies in the rough and tumble political arena.

[x]

In 2016 Democrats didn't have a candidate in 28 races, and Republicans didn't have one in 25 races. This year the Democrats are making a special effort to get candidates to run.

I read that sometimes they promote a no-hoper to see what kind of money or votes he can draw. Also, it seasons the expendable Newbies in the rough and tumble political arena.

That can make sense in a state with a lot of small districts where politicians can move from one district to another. Some political novices shop districts moving from one to another. You have to have money to begin with to pull that off, though.