Sorry if I'm wrong, but doesn't lxappearance only set the GTK-2 theme? You set the GTK3 theme via dconf or set the GTK3/4 theme using the GTK_THEME env var. There are hardly any apps that use GTK-2 anymore; only one I can think of off the top of my head is PCManFM.

Thank you for this

Generally, customization. My understanding is that the origin of its use for describing customization, modding, personalization, etc. comes from the car world where it was used to describe tastelessly modified cars with too many cosmetics, and is most associated with Japanese cars. Folks in various communities where the term has been used to describe customization have occasionally debated whether it has a racist origin (it seems probable that it does, though is now pretty much unrelated to any of that origin), and whether it's innaproprate to use today as a result

It's often used in this community to describe thoroughly customizing your Linux or Unix desktop, and carries sort of the same energy in my mind as like pimp your ride, but for your desktop.

Hope this helps!

Thanks for asking. I just got here and was confused too.