Why is a boilerplate called a boilerplate?

“The term dates back to the early 1900s, referring to the thick, tough steel sheets used to build steam boilers. From the 1890s onwards, printing plates of text for widespread reproduction such as advertisements or syndicated columns were cast or stamped in steel (instead of the much softer and less durable lead alloys used otherwise) ready for the printing press and distributed to newspapers around the United States. They came to be known as ‘boilerplates’.” Source

And here is another version of the same explanation:

“Word Origin & History

boilerplate
newspaper (and now information technology) slang for “unit of writing that can be used over and over without change,” 1893, from a literal meaning (1840) “metal rolled in large, flat plates for use in making steam boilers.” The connecting notion is probably of sturdiness or reusability. From 1890s to 1950s it was literal: publicity items were cast or stamped in metal ready for the printing press and distributed to newspapers as filler. The largest supplier was Western Newspaper Union.”
Online Etymology Dictionary, © 2001 Douglas Harper

Reading the news yesterday, I learned that ‘boilerplate’ is also used by NASA for dummy spacecraft parts. Kind of funny because light weight is a huge priority in aeronautics.

The Ares rocket flight scheduled this week will carry a boilerplate Orion capsule – the size and weight of the manned capsule, but much cheaper to build.

sturdiness or reusability -@Darwin – lawyers also use the term for standardized documents, such as straightforward apartment leases, contracts, etc. I am fairly sure that I saw the expression in one of John Grisham’s novels, boilerplate as a staple of ambulance chasers.