While the hardware may be getting more complicated due to component density and packing more features into a smaller space, many of the tasks required to install components have been greatly simplified.
As an example, here's what I had to do to install my first hard drive (Seagate ST-225, 20M) in an IBM PC/XT in 1984:
Needed correct controller card as support for the drive was built-in to the controller. The machine's simple BIOS had zero support for hard drives. The controller could only be used with hard drives that it knew about, consequently, drives often were sold/shipped with compatible controller.
There were 2 ribbon cables that needed to be attached as well as a power cable. If you reversed either of the cables while plugging them in at best the drive wouldn't work until reversed but could also blow something in the drive or controller.
Once the drive was physically installed, it had to be "low level formatted". This required invoking a format routine in the controller's BIOS by using a program that came with DOS called debug. You would boot DOS froma floppy drive then run debug and enter a cryptic command such as: "g=c800:5". This was basically an address in the controller's BIOS that debug would jump to and start executing instructions. You needed to know how many heads and cylinders the drive had plus some other info that was less critical such as what cylinder write-precompensation started. On a label on top of the drive was a list of which sectors had been determined to be bad by the mfr, you could enter that list to tell the drive not to try and use those sectors. The low level format took a long time (even for a 20M drive) because the the drive was also verified during that time.
Once the drive was low level formatted, it then needed to be partitioned which required you to boot DOS from a floppy and use the FDISK utility to partition the drive.
After the drive was partitioned, you could then boot from a floppy and format the drive. If you wanted to make the drive bootable you entered "format C: /S" which copied the system files to the drive after format and then you could remove the floppy from the floppy drive and reboot.
If you had done everything correctly the machine would now boot to a DOS prompt such as: "C:\". Congratulations, your drive was now installed. Unfortunately, virtually no software that had been written as of now knew anything about hard drives so you were pretty much on your own as far as installing and getting software to run that essentially always looked for the A: drive to read/write.