I CAN UNDERSTAND THE FILIBUSTER RULE...

because I think that's a good way to protect the minority but I can't see the logic behind a hold, which allows a single senator to block a nomination or a bill. There doesn't seem to be a constitutional or historical justification for this procedure, according to the Senate's website:

The practice of "holds" (requests by Senators to party leaders to delay floor consideration of legislation or nominations), which is nowhere recognized in Senate rules or precedents and about which little is known with respect to its origins, has become a prominent feature of today's Senate.