Thanks for your (long :p) answer Jest Phulin.
With any set of rules, there are those that will try to find a way around them. Changing the rules will just result in them finding new ways around them.
I don't see any way to cheat with what i suggested.
There are those that want to be top ranked in the ELO system. There are two main ways to achieve this: Be an excellent player, or "cheat." And by "Cheat," I mean find a way around the system as intended. You seem to think that being able to gain a few ELO from playing players ranked much lower is a cheat.
Yes i think that being able to gain few ELO from playing players ranked much lower is cheat at some point.
First, the ELO rating system on BGA is intended to allow players of similar skill level to more easily find others of a similar skill level to play against, as this tends to be a more enjoyable experience. This is not hampered by people artificially inflating their ELO by only playing against poor players. They will not join tables with truly skilled players. Truly skilled players will still be able to find truly skilled players as opponents, even though there are a few non-skilled players with the same rank. These are the only people that will actually join a table.
With my suggestion elo would reflect real level so this point would be solved.
Second, what is "when elo gap is too big"? In your example, the ELO gain is already only 2. At what point should it be that "an ELO gain of less than X is actually a gain of zero"? In order for non-skilled players to gain a lot of ELO against other non-skilled players, they have to play a LOT of games. Additionally, they have to have either some luck or some skill, as the ELO loss from losing a game against a lower-ranked player is quite large when compared to the gain from playing the same opponent. Lowering the ELO gain when the gap is too big is already built into the system.
I have no real idea but 200 elo gap seems good to me.
Someone with a real 1600 elo has no risk to play some real 1300 elo player.
He will always win.
More, sometimes some player can have 2000 elo level but just started to play. With my suggestion he would have to play players with same elo as him.
So no risk for a 1900 elo to lose to a new account.
Third, there are always ways around the system. One could easily set up several accounts, and manipulate standings that way. For example, accounts FakeAcct01 through FakeAcct10 are set up, and each account plays every other account, and the games are played such that lowered number accounts always win. Then, the "real" account comes in and plays FakeAcct01. They then look like they are a better player than 10 others. This will take quite a while to accomplish, however, and is truly only useful to those people that think that winning the game of life is having a large score on BGA, rather than enjoying the experience of playing.
About the ones who set up several accounts, it already exists.
Player like deszcz did that with maybe like 10 accounts. With or without applying my suggestion it will still exists, so it s not relevant point.
As a side note, any system that forces players to play against their skill level is a "bad idea" (tm). I have seen many skilled players will take time to explain a game to a newb when asked politely. Preventing these games will result in new players not being able to see skillful moves.
With my suggestion about elo system, it lead people to learn how to play instead of trying to play only weaker opponents.
This point seems important to me. It sounds more interesting to make people play better and better and try to learn more and more than taunt them to steal little elo cheating playing mass poor quality games.
I did myself explained caylus to begginers, and i won no elo points.
So people will continue to "teach" even if elo system is changed.
Also real begginers can't really understand skillfull move.
A good evolving curve is to play players from your level and you just learn correctly little by little.
You can also watch top ranked players games as example, especially if those players are really top ranked players