Operating in small windows is how things are supposed to go! You get a 3 to 4 year run where you make the playoffs several times, then your guys start getting expensive and leaving. That's how the NFL goes!
Take a look at the Buffalo Bills right now for a great example, they had a multi-year run, they were able to add a Von Miller to push everything in on 2022, and now they're struggling a bit because they can't keep all their defenders around and they don't have young guys to replace guys who are getting injured more (the Bears signed a LB from them last offseason).
Take a look at the LA Rams - they dumped everything they had on winning a title, took advantage of Kupp and Donald, won their title, and finished 5-12 last year because they hit the salary cap. The Eagles and the 49ers are in a peak right now, but the Eagles lost a LB to the Bears last year and right now they're struggling to stop the run the last 3 games because their LB corps is a bit weak. This is totally normal!!! You can look at basically every Super Bowl qualifying team other than 2 exceptions and you'll find the same pattern.
The only teams in the NFL that are exceptions to this are the ones that have the truly elite coach-QB combos (New England, KC).
Pittsburgh is a totally different problem. Their ownership also flat out sucks. Even with that, they're able to make the playoffs occasionally, but they have been really bad at developing talent (Go check out Gerrit Cole's story here).
Kansas City had a strong multi-year run, made the World Series twice, then had to rebuild afterwards - and their problem has been that their rebuild has gone poorly. They've gone back to being dumb, possibly because their GM had other priorities than finding the best players once they won their title.
Baltimore hasn't made the playoffs in years, but now they built up a load of talent and suddenly are looking at being a top team for the next however many years as long as they don't squander their young talent. They're in a division with the Red Sox, Yankees, and Rays, and they led the AL in wins last year.
The Dodgers have spent a ton of money this offseason, they make the playoffs every year, but they're also on top because their organization is whip-smart. They are able to make trades for Trea Turner and Max Scherzer because in addition to spending money, they also develop talent like mad. They turned guys like Max Muncy, Justin Turner into studs when other teams gave up on them. They aren't getting high draft picks, but they are still churning out prospects that people want to trade for, because they're bloody well run and smart. They've short-circuited the normal cycle by being...really really smart.