The problem is that thankfulness can only be expressed to a person. Which suggests that it is much easier if you can address your thanksgiving again and again throughout the day to a personal God. For Paul thanksgiving is what God desires for his children. It is certainly impossible to believe that thanksgiving ever did anybody any harm. And it is hard to imagine a good argument for a religion or ideology which sapped thanksgiving from the heart.
Thanksgiving is certainly the heart of Christian worship.
And it is to be characterized by thankful praise. Those who enjoy that quality of thanksgiving need no other proof that they have found what life is about.