TO these two statements....
first statement: if you objectively look at the last 4 meetings, 2 regular season, 2 playoffs, they all came down the the end of the game, a play here, a play there, a bounce of the ball, etc. Very evenly matched teams where each team has won 2 of the 4. It is also true that the playoffs is what matters but I do believe there is some amount of "luck" in play here. Imaging we flip coins 4 times, you have heads, I have tails and we decide to call the 2nd and 4th flip "heads". The flips go tails heads tails heads. You won the two "playoff" games.....was there really anything different about the 2nd and 4th flip or did it "just work out that way". A football game is much more complex than a flip of a coin but my point is the teams are evenly matched and because they lose in the playoffs it is perceived a certain way.
Second Statement: The Bills are one of 2 teams who have won a playoff game each of the last 4 years and by doing so they have advanced past the wild card in each, I assume you meant Divisional Round.
As far as the whole post, we have seen this before in various forms, if you look at point differential over the last 4 years the Bills are a huge outlier, if you look at offensive and defensive rankings in yards or points over that same span they are an outlier....the bottom line is they have not been able to finish. DVOA is fancy stats but the conclusion is the same. The NFL comes down to a single elimination tournament. The sample size of playoffs is actually very small, none of that matters because the only thing that matters is if you win. Von MIiller kinda summed it up, keep swinging and it should happen. It does not have to but this organization has a good shot every year with the staff and QB they have.