Photopea instead copies Photoshop’s interface, which is its real asset.
But neither Krita nor Gimp are supposed to be drop-in replacements for Photoshop anyway so that's okay.
As an added bonus with Photopea I have to relearn GUI patterns nor shortcuts, I can apply what I've learned in years of PS usage.
This is an opportunity for FOSS, if the objective is to increase adoption from casual users. I wonder if the GIMP version that was made to look like PS is still a thing
Also if you have a slower computer wouldn't running everything in Javascript be the last thing that you would want to do.
Furthermore if you where to measure RAM usage between the apps I bet GIMP would be far more conservative with the same load.
Also if you are editing images for a living 100 megabyte really isn't that much? Lets say you have RGB images of a resolution of 1920x1080. Sixteen or seventeen of this would be 100 MB already? If you are using layers you quite quickly reach this amount of storage. So the size of GIMP is really negligible.
The only definition of someone with more "limited means", where this would be better is someone who is using a chromebook but still has a 1st world tier internet connection. I'd be happy to be corrected if I am wrong however.