If probate has not been filed, then assets cannot legally be transferred from the estate to beneficiaries/heirs.
If assets are handed out to beneficiaries/heirs anyway, then they may have to eventually be returned to the estate. Suppose a decedent’s creditors were to file creditor claims and those assets were needed to satisfy the claims. Because valid creditor claims supersede distributions to beneficiaries, those assets would likely need to be returned.
Additionally, if you were the one to unlawfully hand out assets without probating them, you could be held personally liable for any damage caused by your negligence.