What was wrong with Slackware's bag full of shell scripts? Maybe I'm misunderstanding what people want an init system for, but I'd expect to need little more t

What was wrong with Slackware's bag full of shell scripts? Maybe I'm misunderstanding what people want an init system for, but I'd expect to need little more than "run these 10 tasks. Potentially, wait for A to finish before starting B". Its job should be over when you see the login prompt. It feels like modern inits are more like a watchdog/messaging system-- which seems like something which would be an optional add-in atop a real init system. I want to run a custom utility at power on. It's not a weird expectation. This should take no more than one line of code to achieve, adding "/usr/local/bin/toolname &" to some sort of rc.local file.