Having an excellent QB is a prerequisite to winning consistently. Without that the rest is futile. But the converse is not true, that having an excellent QB means you will win consistently. Aaron Rodgers, Matt Ryan, Philip Rivers, Matt Stafford are all pretty decent QBs who have various levels of success at different times in their careers due to the coaching plus the remaining roster.
Personally, I am more optimistic about Allen's talents than I am the coaching or remaining personnel including the defense. All players, even young ones, are not on a constant upward trajectory, but fans often think they are, hence the 2020, will be better than 2019, and 2021 even better than 2020. It just does not work like that.