If you follow the discourse around Call of Duty from a certain segment of the player base, you'll no doubt have heard the cries about disbanding lobbies, which has over the years taken on a sort of mythical status that YouTubers and the most dedicated players always claim would make the experience better for everyone if it got removed.
Modern Warfare 2, like its predecessors, disbands every lobby after the match is over, which is likely necessary to how the game's matchmaking works, as it constantly reevaluates player performance and moves them around into more suitable lobbies.
While this doesn't look like it's changing, Infinity Ward has made a concession that could, in theory, keep teams together. Season 5 reloaded - which arrives tomorrow, August 30 at 9am PT / 12pm ET / 5pm BST - adds the Play Again feature.