Because it’s cheap in price and easy to learn. You can find a brand new harmonica from only $16 and learn to play your favourite songs in four to six months. ( If you put your effort to practice 30 minutes every day)
Once you learned how to play Tremolo Harmonica and got familiar with the rhythm and music notes, you can choose your instrument wisely. Also, it would be a good start for Chromatic Harmonica and Blues Harp.
The Tremolo Harmonica usually build in 24 doubled holes model, which you have two rows of holes. The top and bottom holes are the same notes with a slight difference in tune that make the tremolo effect on harmonica.
The odd holes are blow-notes, and the even holes are draw-notes.
It’s an excellent choice to play folk and popular songs.
Are you interested in learning this instrument? Contact me know.