So how would a lawsuits have helped?
It seems that the head of a major conservative newspaper group that had like 50% of German readership during the Weimar Republic joined forces with Adolf Hitler and the NAZI party to advance his own political aspirations. He promoted Hitler in his Papers and introduced him to wealthy people. helping him gain followers and financial support.

Seems to me it another reason to break up media monopolies.

the job of the press is to report the news and as you say be "watchdogs" over gov't.
They don't have to power to fine or jail or send to war.
The power they have is SPEECH.
And the power the gov't has against them is SPEECH. That is not a platitude (unless you want to say that the power of the press is just a platitude as well.)
The power of OTHER press is also used against the lairs.
The power of the gov't to limit monopoly and cartels is also a remedy.

loss of public confidence in various news orgs is JUST as real and effective as
the loss of public confidence in various politicians!
weather or not a news org CARES about it or not doesn't make a difference.
Some media corps are so big that a libel lawsuits wouldn't make difference either and in fact it might embolden them. From what I can tell most libel and defamation suits rarely get into the double digit million mark.
Not to mention that I suspect that News orgs as committed to tearing down a politician, as you say they are, would still find ways to float negative stories regularly that would fly under any serious lawsuit range. AND they'd Hire lawyers to give the reporters CLASSES on how to do it.
Unless the bar for lawsuits was so low that it's make... as i've said... the press leary of saying ANYTHING negative of the gov't . like they are in Russia and many other countries. Where the penalties are lawsuits, lost of broadcast licenses, blocked signals,"suggestions" not to run various stories, arrest, disappeared reporters, etc

the Media ALREADY is weary of running certain stories. Look at the Jeffery Epstein case. An MSM Network reporter HAD the story years ago but it didn't run WHY?.. One thing mentioned, if i remember correctly, was that the ROYAL family called complaining and the network simply thought that they would have hard time at getting access to the upcoming royal weddings!
That's a Foreign dignitary welding influences over a news org.
NO need for a lawsuit.. Simply influence was remedy enough to get a TRUE story off the air.
there's no need for lawsuits. They are NOT the only or an effective remedy.

__________________
Hope is the dream of the waking man.
Aristotle

For there is hope of a tree, if it be cut down, that it will sprout again, and that the tender branch thereof will not cease.
Job 14:6-8

Good.Hopefully Trump wins and sues other media outlets for libel too.

__________________
"There can be no divided allegiance here. Any man who says he is an American, but something else also, isn’t an American at all. We have room for but one flag, the American flag… We have room for but one language here, and that is the English language… and we have room for but one sole loyalty and that is a loyalty to the American people.”—Theodore Roosevelt