Ah, that makes sense. I think part of that is a result of fanatics being much more likely to gather on subreddits, forums et al to shout their highest praises. I'd like to think most people are just enjoying good games, but who knows? Larian's new direction is pretty much limited to making a licensed D&D game and using more up close and personal dialogue camera angles.
One thing I would like to point out though is that they didn't force their origin system into D&D, 5e already features backgrounds in the core rules, and they function exactly as they do in-game. Not really certain where "transplanting" the toilet chain is coming from, either; combat turns in 5e are divided into movement/action/bonus action/free action as they are in-game, there's no AP cost per individual action like DOS features. The only thing Larian modified from 5e's rules was changing around what type of action certain abilities consume.
Origin system is referring to the ability to take one of your party members and play them as if they were your main character, and we already know that there's going to be a fair amount of content gated behind this that someone playing as a custom character won't see for whatever reason, which is how it worked in D:OS2 as well. It's currently not available in BG3 but we know it's an upcoming feature.
Toilet chain system is referring to how party movement is handled, and how you have to 'break' the chain to get party members to split up without the rest of the party automatically following you (and oftentimes resulting in situations where the following party members automatically walk into hazardous terrain and such).
Both of those are basically 1:1 carryovers from DOS2.
