You are right, barmar's explanation makes no sense. Even so, this is a good way to play 2minor rebids over 1NT. If partner bids a suit after your takeout double (instead of 1NT), you will never need to remove partner's bid out of fear, i.e. you double showing at least tolerance for the other suits, partner picks one of these suits, end of story. Removing to a new suit therefore shows a good hand (assuming no ELC). However, suppose you have doubled on a 0454/0463/1453 etc 9-10 count or so (depending on vulnerabity etc), why should you be forced to be dummy in 1NT, knowing you probably have less than half the deck and a decent contract elsewhere? Being able to bid a 5 card suit NF seems more logical. If you do have the strong hand, you can bid 3♦, 3NT, etc, so you lose nothing by playing the 2 level bids as weak.