Not the OP but I would guess its a combination of things

1. The style and motif. I've never met someone who got interested in Linux and didn't immediately appreciate the look and feel of the terminal. People see hackers and fast scrolling text on TV and in movies and it's just fun. Lord knows I was and still am obsessed with CLI and TUI stylings. It brings me joy.

2. It's a lot easier to get started writing a TUI or a CLI. Picking a GUI framework is not easy and many times they are not fun to use. You can only use so many languages to write a GTK app or a QT app. You can use almost any language you want for a CLI tool.

3. CLI and TUI tools are way more universal. I don't have to care if you run GNOME or KDE or if you have GTK-3 or GTK-4 installed or whatever. CLIs and TUIs just work. I can also distribute a single static linked executable instead of a .deb or a Flatpak or something more difficult.

To be fair it was part looking cool and part that the official client Spotify ships for linux is not the greatest. It looked bad and ofcourse used a lot of RAM, that didnt help when i tried to run it on a very old laptop