It all comes down to one fundamental question.

When a moderate democrat becomes a republican... does their tendency to respond to polling change as well? This is a very important question. If people who flip sides also change their response behavior, then EVERY D->R flip is flying stealth. The polls cannot see them.

You have to understand that partisan non-participation bias is such a huge problem that the polls are basically garbage. They might as well be just posting last year's election results and that would be more statistically honest than what they're pitching as polls now.

Because they're using the last election to try to compensate for partisan non-participation bias. This natural result of this is that the polling will tend to resemble the last election.

It all comes down to one fundamental question.

When a moderate democrat becomes a republican... does their tendency to respond to polling change as well? This is a very important question. If people who flip sides also change their response behavior, then EVERY D->R flip is flying stealth. The polls cannot see them.

You have to understand that partisan non-participation bias is such a huge problem that the polls are basically garbage. They might as well be just posting last year's election results and that would be more statistically honest than what they're pitching as polls now.

Because they're using the last election to try to compensate for partisan non-participation bias.