The ability to be multitasking for a musician is a valuable thing. I don't think it's some innate phenomenon or extremely rare. If you willing to spend time on this, you can develop such skill. But to be considered a multi-instrumentalist definitely needs talent, perseverance and a keen desire.
One-man band is so common feature that it can even be called popular. Moreover, it does not matter what style of music to take, cause everywhere you can find a multitask-man, who doesn't care, which tool to use for writing music. But according to my observations, most often groups of one person are found in electronic projects or black metal. Since electronics in its pure form lulls me to sleep, and it makes me sick of black metal, I will write about fusion.
I remembered the project Celldweller, its creator and the only member Klayton (Scott Albert), who is a multi-instrumentalist and just a great musician. During his musical career with his constant search for style/sound/place, Clayton spawned many interesting side projects and gave a push to other musicians who followed in his footsteps.
One of these is Blue Stahli project. One-man band, the brainchild of Detroit musician Bret Autrey.
Back in the 90s, like Klayton, he chose the same creative trails of industrial, electronic rock, nu metal and synth. He participated in the recording of different teams, saved up experience, and only after almost a decade was able to give us his own creation. There are so many genres in this music that you can get confused, and this is the main feature of Blue Stahli.
Klayton and Autrey's projects are not just often compared, but even confused. Personally, I see a lot of similarities, but even more differences. For example, Autrey often uses drum-n-bass rhythms, and guitar and drums in his music are much more aggressive and faster.
Autrey is a good vocalist, drummer, keyboard player and guitarist. This is not the entire list of tools that he uses in writing music.
Blue Stahli project was created in 2007 and was almost immediately noticed by Klayton, who later helped Bret Autrey to become famous. I mentioned that these guys have a lot in common musically. So, at one time Clayton played with Brуе, and Brуt was a part of Celldweller for four years, helped record in studio and was a session musician at concerts. Such mutual aid pushed people to compare and confuse their music.
This is the kind of electronic music I like the most. It has character and less affectation, and at concerts not only a synthesizer is used, but other instruments as well. For example, Autrey plays on the rhythm guitar and often uses percussion.