It does? What about asking saints for help? Or talking things over with long-dead ancestors? Or parents? Or siblings? Because the family members, at least, are part of one's life and living memory. In many cultures, they are honored.
The Catholics who allow praying to saints don’t consider them to be dead, because they believe that they have been resurrected to eternal life. As for family members, or other cultures honoring ancestors, those issues are immaterial as to whether it is sinful or not.
Asking the saints to pray for us is not part of it.
Necromancy.
Why waste your time conversing with demons?
Jesus tells us to pray to the Father, who hears us and answers us.
The time you're praying to *saints* (demons) you are NOT spending talking with the Father.