As music artists in 2021, we have to do so many things ourselves.  We make music, make our own artwork, edit our own videos, etc.  Often times we feel like a one man band, and this is all to create content.  Marketing is a whole other bear and by focusing on one platform you can gain a deeper understanding of of the platform, post effective content that connects with many people and grow your fanbase. After you have built a large enough fanbase, on one platform, you can push your fans to follow you on the others.