The Qi and TC limit was put in place to stop players from earning TC at 100 wins each day. This limit applies to boosters, as someone with a booster will stop earning TC from that booster when they hit the 100 win limit. If a user were to purchase multiple boosters across multiple alternate accounts, they essentially bypass this limit.
This rule should be established for boosters, and not earning TC on an alternate account as a whole, because it is very possible for this to be exploited and potentially damage the economy by over saturating the amount of TC in circulation. This problem simply isn't a concern if each win earned you 10 TC (sometimes 50 TC) per win when you play in public servers, even if you do this on multiple accounts.
Additionally, because all this newly generated TC would be created by one specific individual and only be introduced into circulation through marketing or in-game transfers like duels or bets, the players who aren't actively involved in those activities will continue to earn TC at a snail's pace. The gap between the rich and poor would be wider than it's ever been.

Even without using the current state of the Toribash economy or any specific examples to justify why this change is needed, this rule makes sense.