Coin gifting is quite limited and I understand this is to prevent scams and so on, but a freer coin transfer towards actual alt accounts could be allowed to spend unused coins for items on those accounts.
This should be realizable because you can now have alt accounts under the same email address (Update #2 in https://forum.warmane.com/showthread.php?t=460199), so coin transfers could at least be allowed more freely towards accounts from the same email address.
Update:
To make this suggestion viable, I also propose:
1 for an alt account on the same email address to be able to receive coins this way, a period of time like weeks or month must have passed after the alt account changed its email address.
2 coins transfer towards alt accounts could have a monthly limit. For example you can transfer up to (some amount) of coins towards alt accounts each month. This way coins transfers towards alt accounts should only be viable for the intended purpose.
3 current coin gifting (not towards alt accounts) is separate and doesn't have to be modified.
I think friends accounts are less of a concern generally, but there should probably be some period of time after email address change where you cannot receive coins this way.
I don't think people would change email address to someone else's and wait say a month in order to receive coins.
Or there could be a fixed number of your alt accounts you can transfer coins to (for example 5 accounts, and you can never transfer coins this way to any other accounts after that), and likely other possibilities.
Account A wants to send coins to Account B
Account B lists an item for a desired coin amount.
Account A buys it.
Account B gets the coins minus the fee.
Regarding your updated ideas:
Once accounts are linked, it should be permanent. Unlinking should be done on designated main account through support to negate abuse. If you want to link your alt and main account, why would you need to rotate/change alt accounts, or their emails, unless you're into some rule breaking.
Any kind of coin transfer should have a fee.
Account A wants to send coins to Account B
Account B lists an item for a desired coin amount.
Account A buys it.
Account B gets the coins minus the fee.
I see, although my suggestion would make it simpler to transfer the coins you already have, to alt accounts.
I understand in the past there was less restriction to coin gifting so I hope this suggestion could be considered a viable alternative by staff, that would then decide how freer it is (but limited to alt accounts) compared to existing coin gifting.
If you want to link your alt and main account, why would you need to rotate/change alt accounts, or their emails, unless you're into some rule breaking.
I don't disagree, but if the monthly coins transfer limit is low enough (say for example 50 coins) I don't think much else is needed and would be easier to implement. People do make new alt accounts they might want to transfer some coins to, but if coin transfer is adequately limited I don't think it should be an issue.
But yes there are lot of possibilities, another one would be to limit the number of alt accounts that can receive coins this way in a period of time, for example not more than 1 alt account per month.
There is no need of "alternatives". If you have exceeded your gifting threshold then simply donate more to increase it or use the trading system. Fee is a bit higher, but it's more than enough as backup option.