They are outclassing the competition by some margin and it is for others to catch up. Budgets may mean that only applies to Ferrari and RedBull, but neither can do it.
The problem is a significant portion of Mercedes "outclassing" is in the Power Unit department and under FIA rules you cannot make significant changes to a PU. As such, the others are not allowed to "catch-up" until 2022 when the new PU rules come into play.
And whomever gets it right then will have the advantage until the next PU rules change comes into play.