Earlier quoted context omitted.
There's plenty of jurisdictions where "pasting a scanned signature into a pdf" doesn't produce a legally valid signature. Germany requires some signing software for pdfs - though printed-signed-scanned documents are also legally valid signatures
Show me someone who can tell the difference between pasting a signature in a pdf vs printed-signed-scanned? There was a legislature in America that tried to define pi as 3 so irrational laws are not surprising.
One challenge with potentially invalid documents - when agreements go south and disgruntled employees get a free wrench to toss into the works.
Another motivator is not wanting to risk cheesing off judges.
source: Once prepped federal cases