I've seen disconnects where it has taken my opponent a long time to reconnect, though as I wasn't timing them, I've no idea if they exceeded 2 minutes or not. I've also had one instance when I've needed more than two minutes (I must have come very close to exceeding the four minutes) to reconnect after my PC crashed. It's 13 years old, so takes an age to reboot.
I've only very occasionally encountered instances of players appearing to disconnect because they are losing, while on one occasion a player disconnected and never returned despite being in a very strong position (so strong that when offered the option of forcing them to resign, I resigned), so some disconnects are definitely innocent.
I have the impression that playing etiquette is rather better at the rankings I now meet than those I used to meet early on when playing here, so it's possible that newcomers in particular might be more exposed to bad behaviour. If an opponent appears to have disconnected because they are losing, blacklist them. If they make a habit of it, they'll get blacklisted by multiple players and come to the attention of the site moderators.