I think it's horses for courses.
I hate routine tasks that I do again and again and just can't motivate myself to keep going.
I like to stretch myself and be learning. After a while what was challenging is easy. Some steps take longer to get into the swing of than others. There's stuff I'm no good at or don't enjoy, that I move away from doing, that's why a career zig zags rather than being a straight up ladder.
If when I'd been working 10 years and was on £30k I'd just stopped challenging myself I'd be bored. I wouldn't have liked to progress in the next step there but moved sideways and then found I loved it and started going upwards again.
I might not progress upwards much more in my career now, I'm probably not good enough at the right things to go 'higher' but I'd get bored doing the same thing all the time so will probably still look for new challenges, learning new things in different sectors or something.
But if you love the stability and clarity of task that comes with always doing what you know well, then I can see why staying out makes a lot of sense. It should be better appreciated and rewarded in workplaces as there's value in that competence at each level.