AI is the best at adding standard things into standard boilerplate situations, all those frameworks just makes it easier for AI. They also make it easier for humans once you know them and have seen examples, that is why they exist, once you know those frontend is not hard.
Testing is one of the things that's generally tedious in front end applications, but not inherently complex. There may be lots of config needed (e.g. for setting up and controlling a headless browser), and long turnarounds because tests are slow and shaky. But they are also boilerplatey.
It's hard to generalize but modern frontend is very good at isolating you from dealing with complex state machine states and you're dealing with single user/limited concurrency. It's usually easy to find all references/usecases for something.
Most modern backend is building consistent distributed state machines, you need to cover all the edge cases, deal with concurrency, different clients/contracts etc. I would say getting BE right (beyond simple CRUD) is going to be hard for LLM simply because the context is usually wider and hard to compress/isolate.
Seeing the kind of complexity that agents (not standalone llm) are able to navigate - I can only start to believe - just a matter of time it can do all kinds of programming, including state of the art backend programming - even writing a database on its own - good thing with backend is its easily testable and if there is documentation that a developer can read and comprehend - an llm/agent would be able to do that - not very far from today.
Haven't tried a Figma design, but i built an internal tool entirely via instructions to agent. The kind of work I could easily quote 3 weeks previously.
That said, I still get surprising results from time to time, it just takes a lot more curation and handholding.
