If you're just generating something for fun then DallE/MJ is probably sufficient, but if you're doing a project that requires specific details/style/consistency you're going to need way more tools. With SD/A*1111 you can use a specific model (one that generates images with an Anime style for instance), use a ControlNet model for a specific pose, generate hundreds of potential images (without having to pay for each), use other tools like img2img/inpaint to hone your vision using the images you like, and if you're looking for a specific effect (like a gif for instance), you can use the many extensions created by the community to make it happen.