The author's theme seems to be thinking, "if you take a mundane medieval world and throw in monsters and levels, how would society realistically develop?" And his answer is, "A tiny few will use their wealth and/or political standing to monopolize experience and equipment, solidify their rule, and the common folk will struggle to eke out an existence and fight one another for the scraps. Adventurers would just be disposable gofers for the moneyed classes."
He seems to be a deeply cynical guy.
[eta] At any rate, the few changes from the WN suggest him taking it in a less gritty direction. WN Yajin became a caporegime under Emden rather than how the manga has him try to keep his distance. The order of events is shuffled around a bit, but we're basically caught up, so who knows what happens from here.
To be fair, MC is also outsider, and kinda-medieval life sucked for outsiders. That's why people back then put so much importance into family bonds - even though family backstabbing happened sometimes, most of the time family stuck together to protect the family wealth and power against other families. This is also why life sucked so much for orphans, unless they managed to band together in street gang and support one another - and those gangs wouldn't trust any non-orphan outsider as well.
People also put much importance into credibility, because if people knew you are know to keep your word, they also knew you have something to lose if you break it. MC is unknown for locals, so he can easily scam or betray them and disappear, which makes most of prudent people not want to rely on him in the first place, or at most use him before he uses them.
It's a vicious circle, with his only exit to rise up in power and respect, until people treat him as reliable - except he's wanted criminal, so he can't actually rise up enough to bring wider attention. He doesn't have bonds, so he can't create them. He almost had some back with his healer friend and comrades from party, but all that went to shit, again, due to being wanted criminal. Maybe if he'd fled to a different country?