Of course you’re right, however:

1. If we’re talking about bamboozling people who are either ignorant or willfully obtuse, excess precision is a stupid but useful tool for getting a realistic multiple of 3x-4x past them.

2. If the target audience understands excess precision, the excess precision is a nice little in-joke to flatter them and acknowledge their cleverness.

3. The absurdity of the precision illustrates tha very imprecision of the estimate.