Exactly this. The non-composability and non-standardization of GUI tooling is my main issue with them ; having the same toolkit available to solve every problem takes some doing but is ultimately more efficient.
That being said, it's a hard sell. It's not easy to grok the simplicity of the commandline tools until you've used them to solve what would otherwise be an intractable problem.
Yes, any GUI that doesn't provide any kind of RPC or composable API layer is almost a lost cause to me. I'd personally refuse to use it. With a caveat, though: on MacOS, which I absolutely abhorred in the beginning, having now been required to use for work (instead of Linux), I found the beauty of OSA (Open Scripting Architecture). Holy mother of Turing, I wish there was anything similar on Linux. I had no idea how amazing this thing was. I can fearlessly dig things out of even complex UIs for automation in ways that I can't ever dream to be able to do on Wayland. That still not an excuse - any serious UI should provide a functioning API.
That being said, it's a hard sell. It's not easy to grok the simplicity of the commandline tools until you've used them to solve what would otherwise be an intractable problem.