@Dragou There's a big difference between giving them freedom and letting them walk unprotected into foreign and dangerous areas. I mean, in 99% of isekai stories we have super OP MCs that often remain under the watchful eye/control/protection of the summoning countries, again, because summons are critically important. Here we have utterly weak summons that are even MORE critically important since without them the world will be overtaken by miasma, and they more or less completely abandon them to the whims of fate. This is insane. The actions of the dwarf are seriously lackluster as well, heck one of the MCs nearly died already, a shadow guard leaves a lot to be desired.
Sure the MCs need to travel, but travel is an innately danger fraught activity in any world, especially in one where monsters roam and dungeons overflow. Do kings travel by themselves with strangers? No, as their safety far outweighs everything else. The value of these MCs in this world exceeds that of kings by far, again, because if anything happens to them, EVERYONE DIES, and that's kind of a big deal you know? /sarcasm