Ya that's a good point for competitive scrabble. However today I think a lot of people's main exposure to Scrabble comes from WordsWithFriends (and recently, the new NYT games version). In those games, there's no penalty for getting a wrong word, it just won't let you play it. In that context, I at least think it would be nice to have a setting with a more limited list... it could be like Chess timed variants.
It's obviously an impossible challenge to draw those contours in language. Wordle did pretty well though! And going the other direction, just allowing everything that could possibly a word, just starts getting ridiculous.
Even in casual Scrabble-like games, I expect using a restricted set of words would create a lot of "come on, that's totally a real word, why can't I use it" moments. Most people know at least a few uncommon words that most other people don't (because it's different words for each person).
The Wordle list of legal guesses is not substantially curated; AFAIK basically all five-letter words legal in Scrabble are on it (except on offensiveness grounds, which was a highly controversial decision). If this were not the case, I predict you'd get user dissatisfaction as per above. Wordle's list of possible answers is much more curated, but that's my point; it can err on the side of conservatism, because users won't notice if a word that they'd expect to be on there is missing, whereas they will notice if such a word is not allowed as a guess.