Also you do not just leave a hole but when you thread in a bolt you have now replaced the material you have removed with a bit of steel, so is it stronger or weaker than when you started?
What we have here is different ways to come to the same conclusion.
Some have just drilled and tapped the swingarm with no issues (make sure you use a fine pitch thread).
I use riv-nuts as I like steel treads.
Others insist on added welded bits.
I have never seen any of the methods fail.
So use whatever method lets you sleep the best at night but all will work just fine
