I don't agree. Many 3b1b videos provide a rigorous mathematical argument in the usual sense (i.e., they don't contain every conceivable detail — math papers don't do that either — but the gap from what is explained to rigorous-as-you-like is routine).

As a representative example, consider his video on the Basel problem. The video features geometric intuition, but it is intuition that drives a proof that is being presented. There's nothing hand-wavy about it.