That's only part of their problem.
The real problem is that these types of shows are just so expensive to produce and nobody is watching them anymore. And this wouldn't change even if they started being funny again.
We're really witnessing the final gasps of the historic network programming format as Boomers die off and younger people have moved on to internet-based visual entertainment produced for a microscopic fraction of the cost.
You hit the core of it: nobody watches late night TV anymore. The former TV watchers are watching TikToks on their phones or on-demand web content in the evenings. The TV networks just haven’t realized their audience is gone. People are done with insufferable and insulting content - too many choices these days.