Just curious if anyone knows how and when all the weird beeps and boops and stuff started being used in modern radio we hear today.
If we're thinking of the same thing it started pretty much the same second the synths, vocoders, and other tools got invented. In an entirely sonic media such as radio they where dependent of clear and recognizable jingles to have even the most inattentive listener, like drivers for example, to be aware of changes in programs and notifications without risking confusion. And as such, they often used as unique and interesting sounds as they could find. Of course many channels kept, and still keep, using regular musical instruments playing simple little tunes, but it's WAY easier to design something spacey than to compose it!
Clear Channel is most likely responsible for the fact that most radio promos sound the same. They own at least 1,200 radio stations in the US.