GIMP has been my goto graphics software since the early 2000's and yes, this is true. Several common tasks that Photoshop has baked in or has a plugin for has to be done manually in GIMP. Since 2.10 the plugins have really improved but it still definitely has a steep learning curve compared to Photoshop. Another good open-source alternative is Krita. It has a really good balance between usability and features with a slick, modern UI.