For monsters, their equipment has no relevance for the monster math. And this is straight from the 4e guidelines.
Yes, you could deviate from the guidelines, but the default rule was exactly what you can find on your index card.
To the other points: I don't want to argue about preferences or experiences. There is no right or wrong. I won't deny that your experience was positive and I can swear that mine was not.
To clarify my point: 4e math scaled with your level. Especially later even skills DCs scaled relative to your level. Monsters AC scaled with your level. For us there was no feeling of progression. Just more of the same powers but with bigger numbers. I really fought against that feeling by varying my encounters and so on, but in the end, I failed or better said, it was more work than I was willing to do.
In 5e I open the book and play as it is, without regard of the math. For our games with a lot of different player and over a lot of level it just works steaight out of the book and gives us a good feeling.
So who is right: you or me?
I think we both are right about our experience and I think it is a good thing that we have different preferences.
Arguing that 5e math does not work is just a wrong statement, because it does (in most cases) for us, while 4e math made several of us leave the game.