Amps have as much personality as instruments and they're certainly a part of the bass player's instrument (just as the piano box is a part of the piano) but the source sound is acoustic so the properties of the bass do effect the sound. The electro-acoustic world.I’d argue that the amplifier and cabinet are as much a musical instrument and part of “the bass” as the bass instrument itself. Just as an oscillator by itself does not a synthesizer make. But that would only lead to endless hairsplitting over definitions. And probably end up annoying the rest of the thread while we’re having a good time. So let’s compromise and call it an electro-acoustic instrument and let it go at that.
I'd say rules are hard to cling too because there are basses that sound great and break rules. My danelectro Longhorn 1999 reissue is one. You could get used to the thing on a permanent basis, some do, and it's made of of hockey stick tape and cheep furniture particle board. Right now all I'm playing is a Jack Cassidy, 34" scale is just fine for this remarkable 4 stringer with the special pu set at the right spot and a body that brings out Lots of frequencies...truly electro acoustic balance. DR Blue nickles sounding perfect.