Regarding generative images, it's more of an issue because the effects are different.
Software tends to be a "living" project, so just vibe coding with 0 software knowledge is not yet fully sustainable for maintaining a project. But with art, the AI just spits out a completed image.
The generated images compete directly with the people the data was sourced from, and there have also been many cases of abuse, eg people using AI to impersonate a popular artist and selling comissions under that artist's name.
The copyright situation for generated imagery is also tricky, so people pretending to be artists only to be sharing work that isn't copyrightable can cause a ton of trouble and financial loss for customers.
Most of these issues don't apply to software in the same way. That's why I was surprised by the backlash to this as it's just touching the software side, I don't see this as threatening artist's work.
When I was dabbling in image generation (~StyleGAN2 era), my vision for image generation models was as a support tool for artists (back then I was generating small character thumbnails to help me brainstorm ideas for drawing), believing that people valued art for the human effort. Even then I would have considered what Anthropic are trying to do here as the preferable way to use AI in art workflows.
It threatens because we aren’t just talking about selling your art. Artists get hired at companies to produce all kinds of work that will now be replaced by AI.
Artists get hired at companies because companies have the technology that made the artists work profitable, starting from book printing (public performance -> book printing -> cinema -> tv -> internet, similar to drawing -> photo -> digital). At the Public Performance / Drawing Era artists were mostly poor low class rogues. The technology made them what they are now.
They are protesting against natural technology development. To me it looks similar to taxi drivers protesting against Uber (protecting their right to scam tourists).
Did drawing artists protest against photography? Do celebrities protest against photographers selling their photos taken by them in public places?
They are right to be afraid though. What's really happening here most probably is Anthorpic buys rights to collect user trajectory data. In order to replace Blender users later.