Does anyone really do this to their cooling system?

Here's the excerpt from page 43 of the 1974 Plymouth Duster Owner's Manual. Perhaps I've misunderstood it. It says to "remove the drain plugs in the sides of the cylinder block". I took this to mean the freeze plugs because I can't find any "drain plugs" in the side of the block. So now I'm assuming that they are referring to the single plug that I posted a photo of. I guess what I'm wondering is if you do a better flushing job by using the backflushing tee instead of draining the block like the owner's manual says. To me, it seems like using pressurized water to blow everything out of the cooling jacket is better than simply using gravity to drain coolant out of a hole. Your thoughts?

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That's pretty crazy. Pull out all the core plugs and do your flush and fill and report back to us how that works. :poke::lol:
If A plug isn't leaking I don't disturb them. Just sayin' I am trying to figure out why you feel the need to remove every last drop of coolant out of the system?