Can you provide a source for that claim?

The goods produced in China are cheap because Western economies made a bet that they’d come out ahead by moving their capital out of their own economies and into China. China won the bet instead of them and now has more productive capacity than the West. Why is it China’s fault that the West had poor foresight and deindustrialized itself in exchange for short term profits? Should Chinese workers have remained poor forever instead of benefiting from Western investments?

What about the cost of the signal sent to the Democrats that their current positions are enough to earn your votes?

I would respond: if not voting for the Democrats (and voting for a party to their left) saves one life from climate change, imperialism, COVID, or ICE because it pressures them to take stronger positions on those issues, it’s also worth doing.