if you think a bit harder, you shouldn't be. the data on you isn't just used to manipulate your choices on the market, it also ends up being used to manipulate your choices as a citizen -- politically, socially. You might think you're above such psychological tactics (and perhaps you are, but many many people are not, and whether you believe the democrats accusations of electoral fraud in 2016 or the many accusations on both sides since, there is absolutely no doubt that the corporatization of the internet has played a giant part in the most repugnant aspects of american and world politics since 2016)
Democrats didn't say there was election fraud in 2016. It was that the Russian government had workers on social media posing as Americans supporting Trump's campaign, and that they also got access to thousands of DNC emails due to a spearphishing campaign targeting DNC employees.
What they are probably referring to is that the Clinton Campaign in one of the Rust belt states asked for a recount as "claiming election fraud." The votes were close and within the margin for the campaign to ask. They asked, it got recounted and Trump ended up with slightly more votes after the recount. Then that was it. You know, what normally happens. The Clinton Campaign did not send someone to go do a press conference outside of the Four Seasons landscaping to repeat over and over claims that were repeatingly found false in courts.