re: Is the Dem strategy of bolstering their Poll numbers a good strategy?

Let's tap the brakes. Many of these polls aren't being generated by Democrats, per se, but various news and polling agencies. The rank and file there may be left-leaning, but don't confuse that with some elaborate DNC or Biden campaign strategy.

I think the bias in polling that fooled everyone in 2016 was a product of a general public that has lost faith/trust in the news media, is skeptical of pollsters, and either refuses to participate or lies when asked about their voting intentions.

The messaging from the left has been, and continues to be, that being conservative is to be uneducated or unenlightened, to be intolerant, to be hateful, to be racist, to be sexist, and generally an all around deplorable individual. The left has created a cartoonish caricature of a little over half the country. And if you don't fall in line with whatever nonsense they are peddling today, you will be accused of any number of the aforementioned social sins, publicly shamed, and disciplined officially or otherwise. Conservatives either won't participate or lie. And therefore, I anticipate that we will see the same kind of baked-in bias that favors Democrats and produces wildly inaccurate electoral college models following the election.