[The Detroit Collector]

They are pretty much necessary if you plan on reselling. If you got autographs done personally and only planning of keeping them in your personal collection, they are not needed.

If you plan on reselling and at a reasonable price, they are needed.

Also, they are not always 100% accurate, especially for extremely rare autographs. Vintage baseball as an example. The best course of action is to first see if there is a TPA and then personally review other autograph examples to conclude if the autograph is authentic.