If the returns are legitimate (based on NY's law about releasing private info when under investigation, it very well may be) the fact that he only paid $750 in 2016 isn't the bomb shell. It's the fact that he's sold himself as a great president and leader because of the businesses he's "made" and profited from. His tax returns show tremendous loss (not surprising, Smoking Pat could probably do that for him) but also completely ignorant leverage that no business person would legitimately take on.
Again, I'm not arguing Biden/Obama good > orange man bad. I'm arguing that the one thing people default to when you point out the fact that he's a lying, narcissistic, feeble minded president is that he's an outsider who ran great businesses. For some reason, that qualifies you to be President. I don't buy it. Nor do I buy a Biden presidency benefitting this country any differently. If anything, I think I won't have to hear from, or about, Biden for the next four years, a welcome reprieve.