Just read this and it will answer every question you just asked.
betweentheposts . ca/2022/07/maple-leafs-in-rarified-air/
Betweentheposts . ca/2023/02/the-leafs-are-still-an-illusion/
You don't have to take my word for it. But Howard Berger is a lot more accomplished. I would also recommend reading the rest of his site too if so inclined to do so.
He is a much better writer than I am.
If you're going to post links, I suggest you fix them (remove spaces) first but OK.
The first article is from last summer but OK, it's similar to the second one. The general point is that most cup winners have a franchise goalie and Norris quality Dman and that's fine. The word most is important here and the article does list the exceptions, there have been teams that have won the cup with neither so you're kind of arguing against yourself here. Of course it's possible to win without these components, it's been done before for crissakes and there goes your entire argument.
The most recent example is the 2016 Penguins, so a thinking person might start by comparing our team to that team. I think we stack up pretty well myself, they had CrosbyMalkin/Kessel which is a fantastic trio and those guys drove that team to the cup. That said, I think our top 3 of M&M/Nylander stacks up quite nicely against those three and then we have ROR and Tavares which is better than what that PIT team had at the 4/5 spots. With the adds we've made our depth is quite good as well and our D as a group is much better than what PIT was rolling with. Just because we don't have a Norris quality Dman (though Rielly arguably played like one last spring) doesn't mean that as a group, the D can't get the job done.
What's more important, whether a team has a Norris quality Dman or not, or what the quality of the defence is as a whole? I say the answer is obvious - the defence as a whole is more important. Our team is 4th best in the NHL in goals allowed per game so one glance at that big picture is enough to understand that the teams defence is good enough to win the cup.
You want another reason to be optimistic? Guess who was 4th best in the NHL in 2016, when PIT won the cup? That's right, it was Pittsburgh. They were 4th best during the season, then their D took a massive blow losing their one star Dman for the playoffs and guess what, they still won the cup. So how in the world can you sit there with a straight face and say that it's not possible for the Leafs to win the cup because their defence is lacking?
Murray came out of nowhere to provide quality goaltending for PIT in the playoffs, I see no reason Samsonov can't do the same for us. And who knows, maybe the fact that Murray is now on our team is a sign. You never know, this could be the year.
I hope that helps. Our team is a top contender, it's OK to be optimistic.