[acdha]

I think there are two key differences: a spell checker doesn’t write the document for you or change your style (grammar checkers are closer to that) so your work is still your style and something you can claim copyright on. If you sell your work, that last part can be important. If you’re an artist, customers are paying you for your skills and the more you say a tool can do, the less they’re going to think your time is worth.

They also have a bit of a different market: their customers are people whose work has been used commercially without compensation to endanger their future livelihoods. It may be futile in the long run but I’d imagine there is a substantial market of people who don’t want to contribute to the problem or worry whether Adobe’s terms of service give them rights to screw you.