The priests were ordained with sacrifices and (by our standards) a lot of blood. The consequences of sin include the evil of death. It is what Adam and Eve chose in Eden, and the amount of death and blood reinforced that lesson to the Israelites.
One part of the atonement sacrifice was to ‘cleanse [the altar] from Israel’s defilement and make it holy’ (16:19). After that, the a scapegoat was to ‘carry all the people’s sins upon itself into a desolate land’ (16:22). This ritual was to be a permanent law for the Israelites:
16:34 to purify the people of Israel from their sins, making them right with the Lord once each year.
Along with this came a ban on making sacrificing anywhere outside the tabernacle. The aim was to stop the Israelites from sacrificing animals in the open fields (17:5), and to ensure:
17:7 The people must no longer be unfaithful to the Lord by offering sacrifices to the goat idols.
God surely didn’t rescue the Israelites from Egypt just to have them turn around and worship goat idols (in some translations they are called ‘goat demons’).
There is also a ban on eating (or drinking) blood. The explanation is based on the symbolic importance of blood:
17:11-12 for the life of the body is in its blood. I have given you the blood on the altar to purify you, making you right with the Lord. It is the blood, given in exchange for a life, that makes purification possible.
The bottom line is that sacrifices were reserved for God, who rescued His people from Egypt on the basis of a promise made to Abraham many generations ago. Sacrifices weren’t for other gods, idols or demons.