Chuck Schumer is the whip of the party, as mentioned she isnt even top 10 in performance, her party didnt legalise the activity, other members are aggresive in their pursuit of insider trading information (MTG was part of the most committees during her tenure, but she skipped almost all votes after that, she just wanted the scoop adn then bolted) ...
So why her?
The most common excuse is "well people demand more of dems because everyone knows republicans are crooks", which doesnt explain why more senior leaders, ex presidents etc are the ones hounded instead of her.
how ever surveys by lobbys like the ones owned by the Koch brothers show which politicians people find unlikeable. Unsurprsingly many are unremarkable women, just like Nancy, which makes them easy targets for public campaigns in favour or against.
If you name the most talked about politicans of the past 20 years, outside of the pres (Obama, Biden, Trump) you get mostly women (Sarah Palin, Kamala Harris, Nancy Pelosi, AOC, MTG, Kristi Noem, Laurent Bobert) that is not a coincidence and it explains why no one could pick Schumer, who is senior leadership, in a police line up but can tell you the many dogs Kristi killed