Is the last part really true? I think large companies often hire much more broadly and some don't even have a specific position/team for you until you go through the matching process after you start the job.
I've never been part of such a recruitment process, so I can't comment on that.
My role as a contractor was always highly specific, and so were the roles of my more permanent co-workers. That being said they did tend to switch to mostly unrelated roles every few years or so.
I have a friend who worked in accounting for a large company and complained that nowadays large corporations slice responsibilities into these little bits, because it's easier to train for them this way, but the side effect was that her role had a very narrow scope and she was easily replaceable.
I can imagine some degree of inflation where experienced people are called senior engineers so they can be paid more while the still have room to move around and get training in a new area. But at a high enough level, I'd think the goal switches over to hiring key engineers based on their command of a niche. E.g. a principal engineer with 15 years experience in whatever to lead the new product in that area.
My role as a contractor was always highly specific, and so were the roles of my more permanent co-workers. That being said they did tend to switch to mostly unrelated roles every few years or so.
I have a friend who worked in accounting for a large company and complained that nowadays large corporations slice responsibilities into these little bits, because it's easier to train for them this way, but the side effect was that her role had a very narrow scope and she was easily replaceable.