Designers, engineers, and/or pilots aren't tools, so that's a strange rhetorical question. At any rate, it depends on the crash. The NTSB will investigate and

Designers, engineers, and/or pilots aren't tools, so that's a strange rhetorical question. At any rate, it depends on the crash. The NTSB will investigate and release findings that very well may assign fault to the design of the plane and/or pilot or even tools the pilot was using, and will make recommendations about how to avoid a similar crash in the future, which could include discontinuing the use of certain tools.