My experience with young children is that they can be incredibly welcoming, and accepting. Only a few tend to be like you claim. They generally want to be friendly and be liked.

Unfortunately, they are also still developing and learning social skills. They often can't tell different and guarded from hostile. They will often reflect back how they feel they are treated. This becomes a vicious cycle.

It's about 8-9 that things like clicks can form. Social skills explode in complexity. This is where most aspies begin to fall behind. It can be overcome with training and/or practice, but that gets harder the further behind they fall. By the time it's obvious, catching up is HARD.