Because there are better opportunities on Wall Str... oh wait.
Your second point is key. Corporate society is structured so terribly that the big-box companies pretty much can't get top talent (and fire what little they can get for various forms of "insubordination"). No one with any talent is going to answer to a frat boy.
There are two somewhat parallel (but unequally situated) trees within the modern workplace, the old-style management tree ("visionaries" at the apex, implementers at the bottom) and the technology tree (of which technologists occupy the middle-upper levels and the lower ranks are filled entirely by machines). The tech tree has historically been mounted to a middling position on the management tree, resulting in a scenario where technology people become peons. The world's learning that this arrangement is a fistful of fail, and the mount point is moving up in the structure... but this is a discrete sort of transition, and traditional managers have to be brought kicking and screaming to it, so it usually happens through the destruction of old and creation of new companies, rather than within existing ones. This is one major reason why big-box companies have been slowly melting down, while the bulk of the nation's private sector talent was rather uselessly employed in an abstruse game called "finance".
In finance, technical people ("quants") were often given a designation one-half level above their seniority-based position, e.g. an entry-level quantitative analyst was between the "analyst" and "associate" levels. Finance is old-style corporate compared to cutting-edge startups, but Wall Street has (had?) a better grasp of how to capture talent than most F-500s.