Some people pray to Mary because the Roman Catholic church
has deceived them. Jesus' instructions were to pray to the Father.
The RCC has made it mandatory for Catholics to believe that Mary
did not die. It is one of what are called their ex cathedra dogmas,
declared by Pope Pius XII in 1950. They believe she
was bodily assumed to heaven and intercedes for them,
when there is absolutely zero Scriptural evidence for this.
The RCC has long taught error. For instance, Pope Boniface VIII,
in the Bull Unam Sanctam of 1302, declared that it is absolutely
necessary for the salvation of every human creature to be subject
to the Roman Pontiff. This is blatantly false.
Subsequent to that, Pope Eugene IV, in the Bull Cantate Domino
of 1441, declared: “The most Holy Roman Church firmly believes,
professes and preaches that none of those existing outside the
Catholic Church... can have a share in life eternal; but that they
will go into the eternal fire which was prepared for the devil and
his angels, unless before death they are joined with Her..."