I think if you look at each situation of your examples, they are quite different.
Nashville was a deep team and had world class goaltending. If the Sabres had a Miller or Hasek, I think that would be a legitimate model to explore, but with below average goaltending, I think this team will have to be fairly balanced in a traditional sense to find that kind of success.
San Jose's D issues became a glaring weakness after they added Karlsson. They were a stronger overall team before his addition. The first Karlsson year where he missed 35% of their games, both their GF and GA increased substantially, but their run to the conference finals was pretty luck fueled with the Eakin 5 minute major saving them from a first round exit and then lucking into a depleted Avalanche squad in the second round before getting smoked by the Blues. Adding Karlsson to load up their back end cost them something like 80 goals up front due to cap maneuvers, and the team has been a disaster since.
Tampa is a desirable destination, so getting players to resign there with their weather and tax status is easy, and they were also pretty stacked talent-wise before making their big moves. But by signing all of their D to pricey extensions, we have to remember that they were 17 million over the cap when they won one of their cups. The key thing to the Tampa situation is that they built their core over time, and were already in contend mode before really loading up and making the moves that put them over the top (I believe they had the best record in the east when they added McDonagh)
If Buffalo shows a real trend to being a desired destination for winning, then trading for players that would otherwise likely walk will start to make sense, and they can even bring in cheap vets to fill holes if they ever have that going for them, but until then. they are a rebuilding team with high taxes and the smallest market in the states that not a lot of players prioritize. The sad reality is that some players make more off of sponsorship deals than they do their salaries, and those opportunities just don't really exist in a market like Buffalo, limiting a lot of the draw.