But because they have an insurmountable most (not earned via any sheer technical breakthrough, just through cunningness and being ruthless) they don't need to care if they have too many engineers,whether these engineers are any good, or if their nodejs ec2 instances serve 100 queries a minute. So they just keep it like that.
Companies like IBM needed decades to get into such a rot, modern VC funding and cloud computing have just accelerated this phenomenon.