In pubs a very real problem is that shortly into the game (or even immediately) a player will leave and the other team will not allow a remake. This leaves a team with four players against five, and no help to the team with four. In a late game when a player quits, you will atleast get his items, but early game you are left with nothing.
Proposed solution: Split the gold that player was earning per second amongst the remaining players. If there are four players remaining, they will each get 0.25 gold per second extra, or 1/4th of the 1 gold per second the leaver would have gotten. If there are three players remaining, they would each get around 0.66 extra per gold per second, or 1/3 of the 2 gold per second the two leavers would have earned. etc.
Also, whenever a tower or Kongor is killed, the gold that leaver would have gotten should be split among remaining players as well.
This already occurs in DotA, though not directly. The leaver continues to earn gold over time as well as from towers / roshan, and periodically it is split among the remaining players, giving them support in the uneven 4v5 or 3v5 fight they may be waging.
As it is, if a player on your team leaves, it's usually an "oh well" sort of situation where it's impossible to win. Occasionally if you vastly outskill and outpicked your opponents you can still win, but I think everyone can agree that as it is, an equal skilled team of 5 will defeat an equal skilled team of 4. I think this merits looking into.
Thank you for reading.
One person will get a slight exp advantage and that's only if the person didn't leave via ragequit at around level 7. However, that same person will likely be under the threat of harass from two people in that lane, giving up last hitting and denying power for the safety of gaining experience from a distance. This isn't really a bonus to the person soloing.
Well, Easy Mode is only an extra 600g per player every 10 minutes and it's considered completely game breaking.
Keep in mind the gold from towers and Kongor should also be distributed amongst the team. This also happens in DotA.