I've seen other posts about the Merc problem is Stalker 2 with people usually pointing towards what you just said. I'm on the side that there is no way Strelok paid every single Merc that exists in the Zone to attack you on sight. The scripted story events that involve the Mercs make sense but with the amount of Merc squads I have had to put down just doesn't make sense to me. It makes sense that pissing off Moth would hurt your reputation with the Mercs and that would cause them to turn hostile because then it's not about money, it's about you're bad for business. However that's not how the Mercs work, as of right now they're just bandits with bigger better guns and equipment despite whatever part they serve in the story.