Feels like pre-rose Meruem is a bit underestimated. I'm also surprised to see debates about the difficulty of Meruem vs netero. A serious Meruem vs. Netero is low diff, no question. One regular punch from Meruem would’ve been enough to kill Netero, even though he was an enhancer. Hell, even his tail might have done the job. A mere flick of his tail did more damage to Pitou than a hit from the Bodhisattva. The millions of hits Netero landed did less damage if any, than what Meruem did to himself when he tore off his own arm over a Gungi bet. Says a lot about his raw strength.
Now imagine just one punch enhanced with Nen and bloodlust ,it's overkill. I'd even argue that it was harder for Meruem to precisely cut Netero’s limbs off than it would’ve been to simply kill him. He likely had multiple opportunities to end it, but because he needed Netero alive, he had to adjust his strikes, both in angle and force and was limited to only using slicing motions. He probably could’ve killed him with his tail, but since he might not have had enough control over the damage it would have done, he avoided using it.
It's like asking prime Mike tyson to make a 12year old rookie boxer surrender without hitting his head, torso, or causing any injury and only using one arm.