This is a good question. I think that "Arduino" means a couple of different things, and it's sometimes hard to guess what someone means from context.
There's "Arduino" the old 16-bit MCU board, and there's "Arduino" the development platform supporting a huge ecosystem of MCUs, libraries, and accessories.
For instance, I use the Arduino IDE, but with a variety of dev boards to suit my needs. For my work, I don't need to cost-engineer anything, so I'm satisfied with pre-made modules that I plug into my own application boards.
A lot of engineers dismissed Arduino long ago, and are utterly unaware that the broader ecosystem even exists.
I don't object to a beginner choosing the original Arduino board, for which there's huge amounts of tutorials and documentation. And then, maybe graduating to a more performant board if they take an interest in more advanced or specialized projects.
The second the conversation steers towards actual product selection… that is the time to introduce the MCU space and steer them to the right fit. You do always have to remember that most of those arduino MCU’s have a 5 volt logic level that is more compatible with “LEGO part style electronics” than things like the ESP chips.
555 is obsolete tech. I see this as equivalent to suggesting someone buy an Apple II instead of a modern PC.