[metmom]

It isn’t found anywhere in the Scripture they claim to adhere to.

Thus, it’s a man-made theological system.

[Mark17]

It certainly is a man made theological system. Since Gen 15:6, And he believed in Jehovah; and he reckoned it to him for righteousness, the truth got watered down, and degenerated into the Pharisaic doctrines of Jesus' day, where these nerds thought they could establish their own righteousness, and escape the judgement of God, by keeping the Mosaic law.
Not one of the Noahdites, (modern day Pharisees) has said how long does one have to keep the law. How closely do they have to keep the law, or what happens if they ever make a mistake? Maybe they just think as long as they are sincere, and do their best, that they can please God. That would be what I would call an exercise in futility.
It hasn't worked, since Adam and Eve sewed fig leaves together in the garden. It doesn't work today.