It takes several seconds for the connection to timeout, which during that time if you are queued for a Competitive match, you are committed to it. This rule is in place to avoid the practice of queue dodging.
This means the connection was still being intermittent. The game doesn’t deliberately force you out. More than likely something was happening between you and the server.
As always if this was a one-time issue, try playing several games of quick play to see if disconnection issues are still present. If no further problems arise, then it may be safe to return to Competitive. If you find across multiple matches you are having connection issues, avoid Competitive as penalties cannot be reversed. There is great troubleshooting available for most common connection issues which I recommend starting here if needed:
Please note, the Bug Report forum is not monitored by Blizzard Technical Support, and only by Blizzard’s Quality Assurance Team which tracks for issues such as in-game glitches or bugs as you play Overwatch. Connection issues and crashes are technical support issues. If you need further assistance, please start a new topic in the technical support forum where Blizzard Technical Support and forum MVPs can lend a hand.