It's doubtless unproductive and wearisome to remove seeds from each seeded grape before placing each into a blender. But if I don't remove seeds, can the seeds:
mangle or mar the blender blades?
chip or shatter the blender's container/jar?
The ‘real’ solution is seedless grapes.
Blending seeded grapes in itself isn’t any issue for the blender, it simply won’t care at all… however if you blend too long you will break through the seeds’ outer jelly layer & start to grate the seeds themselves, which will make the resulting purée bitter.