"Back when I was young..."
Maybe you meant to say "three decades ago", but I'm not sure about that either. Two decades ago, building a new PC or performing CPU and RAM upgrades was as trivial as it is now and GPU upgrades were fairly similar to what they look like today as well (uninstall driver, swap cards, install new driver, cross your fingers). Replacing everything but the hard drive on a live system would have probably required an OS reinstall, whereas now Windows pretty much sucks it up, but it wouldn't be rocket science, it would just take an afternoon. And heck, I'm not even sure about three decades ago. In the early days, you often just popped expansion cards into the PC and software that was designed to support it just worked with it, without any drivers being required. Sure, maybe you had to set a few jumpers here and there, like finding an IRQ/DMA/IO combination that was available, but that wasn't as difficult a task as some suggest today, and with that you were often good to go.
In short, while I'm not denying some improvement has occurred since those early days, PCs have always (by design) been fairly approachable and upgradeable, it's just that they used to be new and people were more mystified by them than they are now.