...which is almost always true for any forward-looking prescription. If someone says "you don't need var anymore, just let and const", of course you can append

...which is almost always true for any forward-looking prescription. If someone says "you don't need var anymore, just let and const", of course you can append to that conversation and say "isn't that so naive? what about codebases where you don't have a choice? You should understand var." I feel like the people who are in that situation know who they are. The rest of the world benefits from knowing what subset of the ecosystem they want to work with, as opposed to "you should know everything", which is the most inclusive and the least useful statement.