Why didn't more composers who composed violin concertos compose viola concertos?

1. Who composed the first known viola concerto?
2. Which composer wrote the most violin concertos?
3. Who only wrote one violin concerto?
4. What composer wrote the most concertos?

Who composed the first known viola concerto?

Viola Concerto (Bartók)

Which composer wrote the most violin concertos?

Antonio Vivaldi — many, particularly: L'estro Armonico, op. 3 (1711)—twelve concertos.

Who only wrote one violin concerto?

Beethoven wrote only one violin concerto; I wish circumstances could have allowed for more.

What composer wrote the most concertos?

The solo concerto became popular with composers like Antonio Vivaldi (1678-1741) who wrote over 400 concertos for various instruments. His most famous concertos are a group of four known as The Four Seasons.