Oh totally seen it work myself but I don’t know that it was agile that worked as much as they had a kickass team.
Some teams just jive well. They communicate, they know what each other is doing, and they can plan with minimal waste. And when it’s successful that’s across all roles not just the devs.
In my opinion those teams would have succeeded in waterfall, kanban or their own home brewed strategy as well.
Coming back to code after a year is hard regardless of language. I’ve had C code I came back to after a year that was dead simple language feature wise but hard as hell to follow business wise. I would actually argue more modern features like Union types in typescript has actually made it easier for me. “Oh this function has to handle two cases of objects an object with an id and without an id”