Note, I am not saying this is good or how it ought to be, I am just saying how it is.
Let me ask you - if you were the recruiter at Apple and let's say you owned 5 roles each of which got 2000 resumes (I am stabbing at a number but it's Apple, so likely tons of people jump on every role) - how long would it take you to get through it all?
Back of the envelope: 5 roles x 2k resumes = 10k resumes. If it took you just one minute to read a resume and you did nothing but read them every day for 10 hours that's like 17 working days = so 3+ weeks.
Keep in mind that this pile of resumes is your lowest likelihood of success pile - these are not the people you'd identified priori as targets, they weren't even internally referred, they are just mainly random people spamming you or are very weakly qualified. It "doesn't matter" if one of them is a diamond in the rough like the op was describing - it might take you weeks to get to their resume, and that's only if you don't fill the role w someone from the higher bandwidth channel.
So like I said, not "great" but - what would you do differently if you were HR here?
Hire more HR staff to reduce queue times? Apple literally has $100b+ of cash that they don't know what to do with, they could spend some of it on improving their hiring.
Seriously, it isn't complicated.
Also, there are roles --where time and expertise are a requirement-- that cannot possibly get thousands of legitimate applicants. Some not even hundreds.