[PKop]

No it is not the same with LLMs because LLMs are a multiplier that makes the overall work less compared to without them, and that includes support burden. "Support" is a hand wavy word to dismiss the fact that it consists of writing code and fixing bugs, all of which LLMs can help massively with now. They meaningfully change software engineering which you are ignoring when you assume the same cost of pre-LLM development on multiple platforms.

[SR2Z]

If without an LLM maintaining three apps is 3x the work and an LLM is a multiplier, then it's still 3x the work.

These are not magic. If you have to maintain consistency and security across three different apps written in three different stacks, you are still going to spent 3x the effort.