One thing I've wondered is at what point this becomes a campaign finance issue. Publications (and social networks) are free to only host speech they agree with

One thing I've wondered is at what point this becomes a campaign finance issue. Publications (and social networks) are free to only host speech they agree with. However, advertising in the same forum supposedly has value. If a company is promoting stories for a certain candidate or issue, and banning all stories/posts/accounts against, why does that not count as an in-kind donation, worth as much as the equivalent ads would cost? (Not arguing that this practice is illegal per se, but it seems like it should be acknowledged/reported.)