My bad, that is true. The idea of paper wallet is the fact that the private key is not online but offline and is written on a paper. The idea of generating a HD wallet on an airgapped device and having the seed phrase properly backup on paper should truly makes it a paper wallet too, while many addresses can be saved and be used for transaction.
I have my mew wallet created on 2018 and during the time I am using it is that I don't have any problems with. It is true that paper wallet like mew, metamask important files, private key or mnemonic phrase is not stored online though it is generated through the extension or mew website/app online. Didn't try generating offline yet on metamask but on mew tried many times already and works good on website (did not try app offline).