Questions on Liberty Rear disc on 8-3/4 per MoparAction Articles

Ok I realize I am being stupid here so please be patient. There are 2 MoparAction Articles outlining the very simple upgrade to 2007 and earlier Jeep Liberty discs. I was going down the road of doing the GM Rear calipers and yada..
yada not impressed so shifting gears to these.

Has anyone does this before? Question is basically the first article talks about having to machine down the caliper bracket, 2nd article doesn't mention it, so I missed something or I'm just being dumb....