While I don’t disagree with your point, you picked a poor example. In 2023, John Gibson was 30 years old, and hadn’t had a save percentage above .904 since 2018-2019, not exactly #1 goaltender material. But yes, even if you have a good goalie, if there’s a goalie at the top of your board, you should take them. Odds are it’ll take 5 years before they’re NHL ready and by that time your good goalie could be terrible, declining, or you might have too many good goalies which is a good problem to have. Most goalies should be eased into the league anyway, so a cheap quality backup is beneficial anyways.
A somewhat better example would be Nashville in 2020, who picked Askarov at 11 overall despite having a 25 year old Saros whose lowest save percentage the last 4 years was a .914. Though with that example there is a counterargument that the next 2 picks after Askarov were Lundell and Jarvis, who would make the Predators a better team now.