I'm not entirely sure what "bottom" you refer to here. From what I see, there's a misalignment: Lots of senior people lose time doing work that doesn't require senior people, because there aren't enough non-senior people available to do that work. The solution to this is seen as hiring more senior people, which fails, because while there are lots of junior people, no one is making them into senior people. This results in very little hiring at all, and what hiring there is is focused on shuffling senior people between companies that does little to address the problems.
Then you end up with a lot of people with "senior" titles, but their actual seniority of experience varies wildly. Lots of talented people fall to the wayside because the primary way of becoming "senior" (in terms of capability) is giving you time and seeing if you draw all the correct conclusions and lessons by yourself (which also requires the work you get to help teach you those lessons).
So the industry (in terms of people experience) is bottom-heavy in the work pool. Places that can afford it are top heavy in talent+experience, and everyone else is bottom-heavy in low experience, and neither type of place is doing anything to really address their problems long-term.