If we had multiple "Karma sources" like in BTT, things would be different imo.
While I see the suggestion you are trying to make, we do infact have multiple karma sources, they are all the users who are Senior above. Again, this isn't like BTT, because karma doesn't run out. If there were no merit sources at BTT, then the merit would run out. There are no official "karma sources", and yet karma continues to be issued. I otherwise don't think the solution is to further centralise the distribution of karma among an even smaller group, which is effectively what would happen with these so-called sources. That's the major flaw in the merit system which we should be avoiding, not adopting.
What you are saying is that you are against a decentralization of the karma distribution system.
For now, we have 2 people that can give dozens/hundreds of karma in a single transaction. Adding more users to that list would make it less centralized
That's not what I'm saying no and your math doesn't add up here. Based on karma logs, the number of Freemind gives is only a tiny fraction of the total number of karma issued (maybe 1% let's say).
What you are suggesting is having a smaller group of users, even respectable ones, who send what would likely be the majority of karma issued per month. Assuming that with say 50 merit sources (based on 50+ users that have 250+ karma that could be eligible), then suddenly that 1% could easily become 50% or more. Thus, the majority of karma would likely no longer be from all senior+ members, but instead a small (likely unelected) group of users. That would obviously centralize the distribution, not decentralize it.
Even if it were only 20-40% of karma sent, it would centralize a big chunk of the karma to a smaller group than it currently is. Further decentralization would be something like lowering requirements for eligibility to issue karma, to say full members, then there would be more karma sent from users than there currently are, an increase of 63% issuers to be specific.