The role of bass function in music just over the past 100+ years should be common knowledge to every bassist here, regardless of which instrument we choose to play.
The upright bass (aka string bass, double bass, contrabass, etc) has been around in varying forms dating back to the 15th century. It's changed in terms of design and materials, but is relatively unchanged since the 19th century. It's the lowest pitched of the viol family, and serves that bass function with both arco and pizzicato technique in orchestras. And it's been widely used in jazz and other popular music forms through the 20th century.
On the brass end of things, the tuba has also been serving a bass function in music. It's been used in a variety of ensembles including orchestras, and traditional New Orleans brass bands. In fact, it's common for some bassists in the New Orleans tradition to double on tuba as well as upright bass. Why? Because it's impractical to march while playing an upright bass. The tuba & it's cousin, the sousaphone, are much better suited to marching ensembles that are a big part of the New Orleans style.
The electric bass is still a very new instrument in the world of bass instruments. And it can play parts that are in the pitch range of it's predecessors, the tuba and the upright bass. Electric bass continues to evolve in terms of it's design, which is a natural part of the process.
And we've also seen developments on the keyboard front in terms of those instruments filling the bass role. Organs were the earliest keyboard instruments that were able to fill that role, but were impractical to transport. Organ-like pedals have been used for synth purposes, with players like John Paul Jones and Geddy Lee using them to play bass parts with their feet while they played more traditional keyboard parts with their hands. And keyboard technology has evolved, with synth bass being generated by early keyboards like the Moog. Those sounds seem to have found a niche in pop & dance music.
Now, I've seen an increase in bass players in pop music who double on electric bass and keyboard bass. That seems to be in increasing demand. But still, those musicians are fulfilling a BASS ROLE in the ensemble. It's just a different instrument that's being used to play those parts, and it's the nature of the instrument that's offering a different timbre/texture that some artists want for their bass parts.
