It's reasonable to at least expect that. It's their job after all, while for any single voter there is a lower standard you can realistically hold them too and less time available to verify/debunk claims.
On top of that, there are also instruments that help the voters track whether politicians are engaging in corrupt lobbyism like voting records + donation / campaign contribution records, though few countries do that to a degree that it forms a cohesive anti-corruption framework. None of those measures exist for individual voters.
That more democracy is more attackable is not a coherent position. More democracy means more people power. But people being powerless to resist misinformation campaigns means that they do not have power. Which means that it is not really democracy. This is the same as saying that democracy is being undermined by wealth inequality. If money can buy political power and money is unevenly distributed then it’s not a democracy.
If one was actually interested in actual democracy one would fix that misinformation asymmetry.