There's always going to be an exciting top 1-5 prospects in the next draft that, once they're fully mature, would be able to help at the top of the lineup, possibly the top of the NHL. And yes, generational drafts come and go, but looking back, the world generally seems to be pretty poor at actually ID'ing the truly deep drafts other than the ones that smack you in the face (Ovie/Crosby, Malkin, Matthews, McDavid, 2003).
We can't just keep tanking for the next best thing. Schaefer this year, McKenna next year, DuPont the following, who knows whose kid the year after. Unquestionably all of them would give us a chance at a dynasty -- but the chance of picking any one is no more than 25% at best, all the while you are harming your own already-elite prospects' development.
I believe culture changes with winning, I'm not quite as worried as others about becoming the Sabres, but I also firmly believe that early career development matters and Celebrini/Smith/Eklund would be better players playing on winning teams in their first few years than they would be playing on losing teams. Couture wouldn't have had as good of a career if drafted to a bottom feeder, nor Hertl. Kane and Toews wouldn't have been as successful if they were at the beginning of the CHI rebuild rather than the final pieces.
If we're still talking about being truly in the running (and not just lucky) for McKenna/Verhoeff, AND DuPont, then OK, but then we aren't really going to be in our window until 2035 (10 years), which would match the very longest of rebuild timelines that have been successful (e.g. Avs - 11 years from Landeskog to Cup, 9 years from MacKinnon; 13 years from the failed core piece Duchene, which would be our Eklund or Smith). Hell, it's 10 years since McDavid, although you and I and others know that the Oilers have absolutely f***ed it at every turn.
By 2035, Celebrini/Smith will be good-not-great, or great-not-elite pieces having suffered through 8-10 years of mediocre hockey before the new youth truth saves them. You don't want to pull out of the rebuild too fast, but if we pick top 3-4 5 years in a row, it would be the first rebuild of its kind to be successful.