There is definitely demand for further compression / pixel size limiting after upload.
Imho it should be allowed to upload big files but optimize / downsize them on the server after upload based on parameters from admin config.
Specifically for mobile uploads it would be beneficial to downsample them while keeping high quality / low compression (then to keep high res and compress photo with loss). Phone lenses are very low quality and even that there is high megapixel (usually it is just marketing) chip it doesn’t have any more pixel information than reasonably downsized photo.