What youre stumbling on is these “big tech” cos are growing horizontally when possible, and its normally local engineering roles that used to seed build and manage new teams. Thats why there some pretty extreme reactions to promotion process or senior role interviews. Yes, knowing how to organize a team, mentor junior developers, do market research, evaluate customer feedback, model marginal cost, and write a business proposal are
key skills over the lifetime of those senior ICs. Yes, I could backstop those areas for my team mates today. But once we succeed each of those senior developers on my team will fork off to their own team and repeat the process, thats how we scale out.
A corollary is these self organizing teams add up to self organizing business units. The teams know what to build because theyve at read & internalized what matters to the business. And senior members should be involved with the 6-12 month planning cycles that happen across that business unit. So their day to day execution is informed by, and happens in the context of, the larger business. Think of something closer to hierarchal federation than directed work silos.
WRT to “lighting money on fire” there are teams that look like that. But thats generally a speculative investment with a medium term (~2-3yr) goal theyre working towards. This is business, so its not free or infinite, and in a sense their efforts are competing with the alternative efforts that could be more profitable.