https://www.photopea.com/ A free browser based image manipulation tool with an interface familiar to Photoshop users

I have done a little bit of reading but I’m still not sure what the issue is. Is it that Threads will take over and defacto become the entire Fediverse? Because I think that would happen whether or not Mastoson/Lemmy instances choose to defederate. Is privacy the concern, and if so, wouldn’t it only affect people using Threads?