By that logic we cannot take Lord of the Rings seriously or Star Wars. Or any epic heroes of legends and myth in the past. Because they are built upon things that in reality today we find absurd.
I can't take the story of Turin Turambar seriously because he's fights and kills a Dragon, a mere human doing that.
The reason I find Batman absurd is how often we have to lower everyone down to Batman's level in order for him to get wins.
Turin had luck and an ambush. He happened to be at the right place at the right time and caught Glaurung offguard.
When Superman fights Batman, there's always something holding Superman back. Mind control rendering him dumber. Not wanting to fight Batman. Or just Batman's invincible Plot Armor that keeps Superman from ever using his powers.
Batman can somehow move fast enough to remove a rock from his belt to weaken Superman. A being whose mind and body moves so quick that he once flew through a moon orbiting Saturn. Given that Saturn is 1.0116 billion mi (1628012390.4 km) away and let's say Superman went through one of its farthest
moons which is 8,048,000 mi (12,952,000 km) away, that still means that Superman traveled and navigated 1.0035 Billion miles in 4 minutes.
I mean, that's just stupid. That's a feat that breaks Scientific Reason. But this is a universe where Gods join Superhero teams all the time. So, I'm actually ok with that.
But Batman gets absurd that he's continually stressed to be just a normal human that somehow angles his body to punch harder than metahumans. That he can be fast enough to catch Superman offguard... A Superman that can talk and sometimes keep up with the Flash. That anything Batman can do will somehow register to Superman at all.
And Darkseid is usually stronger than Superman. Batman fights Darkseid to stand stills. Batman dodges Darkseid's Omega Beams. Batman isn't a stain when he's touched by Darkseid.
Batman regularly does things Metahumans can't come close to doing simply to keep him relevant. They won't give him powers because they want people to root for him, but they gave him the most OP power there ever was: Plot Armor. Everyone will be on Batman's level, yet no one is allowed to raise above his.
To me, that's what makes Batman Absurd.