Mahomes is on par w/ most of those QB's, and has 2 titles already. Allen is kind of close to Big Ben - very similar styles and quality of play. Burrow has a ton of potential, but has had a couple of tough injuries thus far in his career. Other guys look like they have potential to be really good - Jackson, Lawrence, Tua, Hurts, Purdy.
Mahomes is the one that everyone already acknowledges, and I mentioned him specifically, so I'm not sure why you're putting him here. Allen is a chucklehead, just like Roethlisberger. But Roethlisberger got to the AFC championship as a rookie, and was a SB winning QB in his second season. And, still, nobody who's not on a cocaine binge tries to argue that he wasn't the #3 in the three-way battle for AFC QB supremacy. Burrow has already missed huge chunks of two seasons, and is 27 years old. Brady had 3 titles at 27, and Peyton had an MVP title, while having been top 5 or better in the MVP voting 3 times, and would then go on to win his second consecutive MVP title at age 28.
The "last era" features multiple QBs that are argued as top 10 guys. The current era has Mahomes and a bunch of wannabes. They have time to develop, but to say that there's not a big drop is just insane.
You're comparing complete careers against guys who are mostly still in their 20's.
Until we develop the ability to time travel so that we can know what the players of today will become tomorrow., we can only go by what we have.
Like I said - I just don't see a huge dropoff in the quality of QB play. People forget that just about all of the QB's you listed had terrible stretches, too. Now when most of them are retired, it's easy to look back at just their great moments.
Brady never had a terrible stretch. Manning had problems winning in the playoffs, but he Elwayed it in the end, after having earlier won one in 2006, and he never had a terrible stretch unless you're talking about losing to Brady. Roethlisberger had a late career decline, but didn't have any real "terrible stretch". Rodgers had to ride the pine behind another all-timer (Favre), but he then won the SB in his 3rd year as a starter, and has never had a "terrible stretch". Warner hurt his hand and was never the same, but he still made it back to the SB in 2009, at age 37. So the only one I mentioned that's had any kind of a "terrible stretch" was Brees, and he was a late NFL bloomer who had to overcome a major shoulder problem before hitting his prime.
So, again I'll ask: You're kidding, right?