There are bad people in every community.
In the case of Afghanistan, it's the opposite, there are good people in the community of bad people. I haven't seen any of them (good) myself personally, but I'm sure an anomalous and miniscule amount exist.
No offence, but I don't know if you've been living under a rock, but it's quite a well known and widely accepted issue regarding the deep rooted hatred and ethno-racism Afghans hold against Pakistanis. It's a fact at this point. Go all over social media, in real-life (will be a little less as they have to control themselves), or any Afghan platform and you'll see that hostility first hand. According to them we are the cause of all of their issues, and worse than the Jews, "daal khors".
Even, hypothetically, if Pakistan and Afghanistan were to merge, it wouldn't last long and a civil war would erupt due to the things I mentioned earlier and a conflict of interests. Bangladesh part 2.
Encouraging progression and modernisation is already hard enough currently in Pakistan because of a negative mentality, but it's thousands of times worse in Afghanistan. It would be a conflict of mentalities and would hinder development. Their mentality is generally backwards and regressive, it's pretty evident, especially towards women. It would be a disaster with more decades wasted.
All I wish for is peace at the international border we currently have, and a neutral relationship with Afghanistan at the very least, and a Pakistan that doesn't look at castes/tribes/ethnicities, but simply a person's merit. That's enough. Maybe in the far future if things progress in aforementioned areas, a merger can be considered, but currently it would make the situation worse. All the best to them.
But it's scary to me how a Pakistani is unaware or refuses to accept the elephant in the room considering everything that has been going on.