If you were to provide Photoshop as a Service on a sufficiently large scale, you would also be expected to take all reasonable measures to prevent it being used to disseminate CSAM and other abusive material.

So, no different to the standard that X should be held to.

And people do do this and have been making crazy and creepy pictures online since its inception. It's never been that much of an issue until now.

In UK law, it isn't.

The practical difference is simply that now it is happening far more frequently.