I don't think that's completely true. I think you ultimately win with your depth. Most teams in the playoffs have a very very good top end. What separates a team like Vegas and Edmonton is the depth that Vegas has in all positions. There was no way Edmonton could counter since Vegas had 4 lines coming at them all game and a deeper defensive core.
The teams that win have both depth and the top end players. In the playoffs and especially as you go deeper you see the teams with depth really shining through. Seattle last year is the perfect example of a team that was very well rounded but that did not really have any top end talent. They beat the Avs who undoubtedly have better top end talent at forward and on defense. They beat the Avs because everyone played their part and they played a strong system game.
It's the same thing for a team like Tampa, they still have a strong top end but their depth has suffered a lot with their best players getting new contracts. The league is now at a point where the window to win is pretty small and the competition is harsh. You have a chance to win when you have your best players under team friendly contracts and you are able to fill out your roster with players that can matchup with the other teams best players or if you have a bunch of guys who can contribute on ELCs. If your bottom 6 isn't able to match against good players you might make the playoffs but you're not winning the cup.
I think for this team the defense is set. I think that's the area where you can look at and say I think we have the pieces to make it work and the depth to withstand injuries. On the forward front though we are lacking quite clearly. If Kubalik produces and plays a good all around game I think we have the top 6. We arguably only have 1 legit 3rd line player right now with Pinto, let's see what happens with Greig he might be another. I think you at least need another 3rd liner. Joseph is the type of guy you want on your 4rth line who can step in the top 9 when injuries will come, and they will happen. Then on the 4rth line you have Kastelic who'll be a staple there. Kelly/MacEwen are 13th forward material. Can Sokolov/Crookshank/Reinhardt take those spots? A lot of question marks and that's not even considering that we will likely face some injuries.
With Kubalik being very streaky you hope he can own that top 6 spot. If one of our top 5 forwards gets injured we are extremely thin really quick (Same situation as last year). We're missing probably 2 bottom 6 forwards to really take the next step and compete with teams like Buffalo and New Jersey who are getting better and better with young players coming in to their roster.
I think a guy like Laughton would go a long way in making us tougher to play against and give some trouble to other teams top lines.