I think this is actually due to incompetent teammates.
Survival on steel path spawns enough enemies such that you'll never need a life support capsule. But, if you kill all the enemies around you then new enemies will spawn, but some of the new spawns will be near your teammate(s), not yourself. Therefore, if a teammate is killing very slowly, after a minute of play all the enemies are congregated in their area, and none are left in the areas where the fast-killing players are.
So, if you want to enjoy survival without these problems, your options are either to play it solo so all the enemies come to you, or follow your teammates around to make sure you don't get that buildup of enemies not being killed.
Personally I choose solo, since this works well for me. Ideally the game-mode wouldn't have this issue, and perhaps that's a good idea for a rework (something about enemies prioritizing spawnpoints near the high killcount players?)