Web services and AI in general are completely different things. Web services that generate AI content want to avoid scandals so they’re constantly blocking things that may be in some situations inappropriate, to the point where those services are incapable of performing a great many legitimate tasks.
Somebody running their own image generator on their own computer using the same technology is limited only by their own morals. They can train the generator on content that public services would not, and they are not constrained by prompt or output filters.