Taking my paycheck and multiplying would be an excellent measure of my yearly salary. I don't understand how that analogy is meant to imply that the approach is nonsensical.
But then the analogy doesn't work at all? ARR isn't calculated by multiplying revenue to 30 years and then saying that that's 1 year's revenue; what criticism is being made here?
they pick some month with the higest revenue. Unlike your income, a business makes different amounts each month based on some trends and many other factors, and they can varry wildly.