Originally posted by TheHulkster👆
While it's a limit, it has never been shown to be a major weakness.
The Beyonders are simply confined to their own sequential timelines. That's why Doom was able to time/universe-hop without them knowing in order to create his Rabum Alal alter ego, and assemble the Owen-Bomb.
...But it's not like time is a 'major weakness' to them, in the same way that Kryptonite is a 'major weakness' to Superman. Lol.