Overwatch's long-awaited role queue feature is going to stay in beta a while longer due to a bug that caused matchmaking to be as reliable as a Ubisoft's AI. Competitive queue will be disabled entirely until Blizzard works the kinks out.
Season 18 isn't off to a flying start in Overwatch. It appears that some bug caused the game not to consider past ranks and would pit Bronze players against Grandmasters.
Such encounters were not pleasant for anyone - no one likes getting beaten down to a pulp and while it could be initially fun for the Grandmasters, they grow tired of pub stomping quickly. The best Overwatch games are the intense ones, right?
Anyway, Bill Warnecke posted an update on the situation on Sunday, 1 September 2019, stating that the Role Queue Beta Season will continue for a while longer, before Season 18 starts "early next week". While not explicitly stated whether he considered "next week" to be the one starting on 2 or 9 September 2019, it is safe to assume it's the former so the delay shouldn't be major.
Players will see "Season ending in less than a minute" on the Competitive card in Overwatch menus, so if you wondered why that is, there is your answer.
A post on the official forums confirmed that Blizzard's schedule does not wait for weekends to wrap up in order to kick off a new season, which could be why role queue and Season 18 started in a less than optimal state. While no one on the forums really has an official confirmation or inside knowledge of Blizzard's workings, it's possible that weekends are handled by a skeleton crew.
Anyway, the delay should be over soon and if you are eager to start chasing the ranks in a new 2-2-2 setting, the wait shouldn't be long.