If the Buddha appears in different forms to help beings why the Bodhisattvas stay at the edge of the enlightenment?

If the Buddha appears in different forms to help beings why the Bodhisattva stay at the edge of the enlightenment? Can this be just an upaya to keep followers from the obstacle of attachment to attaining enlightenment? Or prevent arise of false Buddhas?

Enlightenment

From what I have read in the Chinese version of the Tipitaka, and my intepretation of it, the Arhat, Bodhisattva, Buddha all have achieved enlightenment. Each without distinct from each other. It is what each of their vow and the path the achieve the enlightened state that differs, and ultimately the vow will define their function in the bigger sense of Buddhism cosmology.

Soteriology vs ontology

Since Buddhism is better described as a path rather than a religion, we can find many soteriological doctrines in it. The problem will arises when we take a soteriological concept as an ontological one. Here, I agree with our friend: the Bodhisattva path serves as a method to cultivate selflessness and compassion among people. The proof of this idea can be found in Mahayana literature: for example in the Diamond Sutra we read that in fact nobody would be liberated.

Buddha - Bodhisattvas

In my oppinion, try to look at the Bodhisatva ideal as an approach to the practice of the Way, not as a spiritual Buddha's assistant. Otherwise we can end up in contradiction because for example if an infinite number of beings waiting for liberation, must be only one(!) Bodhisatva (understood as being really existing) which vow to liberate other beings. Or we can end up in a other funny situation where many Bodhisattvas pressing each other to liberation for example... and so on and so forth.
Bodhisatva ideal changing accents rather from ego to others in my oppinion and it is better to look at it as idea. On the other hand, I firmly believe that spiritual forces are real and helping sentient beings.
If everything arising in dependancy it is not possible to obtain the ''self''awakening in the style of a hermit Arhat. "Self" awakening is contrary to the foundation of Buddhism and in my oppinion this was the main reason why Mahayana was set up and why ideal of Bodhisatva appeared.
If we look at the awakening from our human point of view as the path that we have run or thing which have to be done, we can do mistake. Dharma does not have the edge of enlightenment, or the place with starts & end points, I presume.