Dealing is another story but I don’t believe anyone should be taken to jail purely because they are found holding a small amount of substance.
That system only ensures addicts or light users become jobless violent criminals down the road. Most likely dealers like you said because a drug record prevents them from getting a regular job ever again.
Possession laws also allows cops to plant tiny packages and imprison anyone at will to boost their felony quota (or whatever other reason they feel like)
Or they become drug dealers to support a $1500 a day heroin habit.