Wrong.

“GIMP is a cross-platform image editor … Whether you are a graphic designer, photographer, illustrator, or scientist, GIMP provides you with sophisticated tools to get your job done.” - gimp.org

Shape tools is a universal basic tool for any software that handle some sort of image creation or addition.

Photo editing, general image editing, painting software, page layout design, vector design, PDF editor, all of them have one.

Photoshop, Microsoft Paint, Clip Studio Paint, Krita, Photopea, Pixelmator, Affinity Photo, … all of them have shape tools.

Heck, even Microsoft Excel and Word even have one.

EDIT: Shape tool is planned, not yet WIP. Source: GIMP Roadmaps

Even if people know fediverse, if the content they want doesn’t exist here, they won’t stay.

There are Japanese Twitter refugee to fedi (especially Misskey) several times. A lot of big creator doesn’t stay as they want to get the highest number of engagement to keep their (art) business afloat.