I also think it's because some ppl will only see the mc side as opposed to others. They'll be like "Oh they had it bad but our mc also had it bad so..." especially when the ml is the seme... this is just from my observations...but if the roles were reversed and the seme was the mc then they'd understand. (I don't think I explained this properly but this is just what I've seen from some ppl...)

I thought this is going to be your typical angst hurt bl where our poor omega MC has to suffer at the violent alpha ML, but it turns out not the case. The overall story gives off "My happy marriage" vibes
From what I gather, people seems to understand MC's background and his thinking but are glossing over the fact that its the ML who's actually had it worse and he's still decent. His entire existence is not even out of love or duty or need but rather a golden trophy used by his parents to secure their succession and inheritence. He's literally bioengineered baby (CRISPR baby for real life comparision) specifically tuned to have hyper dominant gene with no regards to overall health and well being of the baby and so he's very frail. But the people who forced him into existence treat him like effing pariah. He never asked to become alpha and yet he's treated like a psycho from childhood, this is going to heavily impact the person when they are raised in such environment. His grandpa drilled him the belief that he is better and others are lesser than him and thats why we can see his thoughtline being "he's recessive but fine, im an alpha i can easily dominate you" not because he can, because he's taught like so. Which is ironic considering the gramps is a beta. Plus he's constantly being bullied and antagonized because he's alpha? Man has every ammo for him to justify becoming villian but he's still decent. He has every chance to use and abuse the MC to his satisfaction but he treats him very well and he takes care of him
And as for ML's brother, I sympathize with him. Imagine cleaning up after your brother all the time but being ignored by everyone in his family. Having worked twice as hard and yet still not being recognized and being passed over to your own brother simply by virtue of trait. But he necessarily cant hate his brother too because he knows his brother didnt become this way but rather forced to be this way. Its part jealousy, part anger and part brotherly love. Beneath this chaotic story lies a very complex dynamic between MC, ML and ML's brother. and as for MC's twin, pretty sure he's a spoiled lil bitch.