Four players had to compensate your absence and you damaged their player experience. Would you have posted here if they had lost the game or surrendered while you were disconnected or if the jungle had crushed you?
You couldnt know how long it would take you to reconnect, so its a coincidence you attended the end of the game. According to LoL rules and common sense, you dont deserve the LP. Beside rage quit, another abuse could be blackmailing into AFKing and not even disconnect but staying in the fountain, watching whats going on and deciding to resume playing or not.
https://euw.leagueoflegends.com/en-gb/news/dev/dev-ranked-and-matchmaking-in-2020/
"Game Ruining Behavior - We’re attempting to develop better ways of dealing with disruptive behavior. Examples include better detection and punishment for behaviors like intentionally feeding, AFKing, win trading, and griefing, in addition to giving more frequent feedback when we’ve taken action on unsportsmanlike behavior you reported."
Abandoning a game, for whatever reason, might become even more punished in the future.