Those seems like such basic and tablestake features of such a platform, that I've assumed they all do something like that already. Is that not the case? Is it vibecoders who aren't programmers who are building these services or what's going on?

Yes, vibe coders are telling prompts to build web apps in IDEs like Windsurf/Antigravity, and it sets up the local environment, but getting that from local to web is still a pain point. It's a hole in the market with potential for a firm like Docker that needs to monetize without upsetting its community. Remember, vibe coders are more enthusiasts than professionals. Check out /r/vibecoding on Reddit for an idea of the general market that would use something like this.