Followers are root of artist popularity. So, to be popular you must have to acquire followers for your music. Followers are also considered as “marketing mouth” of an artist. They work for you without payment and they spread love for you.
In modern time, followers are counted as fans/ followers number on your social media/ platforms. Like, Facebook and Twitter, spotify also has its own system to gain followes for an artist for his music .
But, it is not an easy task to reach to your right audience who can be your fan in future. For example, if you are a folk artist and rech to rock music lovers they can not be your fan. Because they love folk songs. So, it is the most inportant task to marketing agency to reach to right audience who may love your work.
That is the main reason, that artist need to buy followers promotion services from expert promoter to gain real and engage followers for his profile.