Don't want to make Kai mad but:

Except for lacking termination on clock, and using a real reset chip, I used that scheme for years. You can either believe me since products shipped out the door, or not believe me and come snooping for some other programming cable with buffers in it. I have used between 6 inches and 25 feet of cable (DB25 fully populated extenders) on the PC parallel port, with only a 100-150 ohm resistor on the MISO line to the PC.

Sometimes programming had to be attempted twice. It's not necessary for the programming process to be perfect unless that is what you are selling, and it's overkill to include parts that will only be used at factory once.