Yeah, the chain system is not getting better - companions are stuck all the time and often follow through fire and other perils. It really is annoying.
I haven't noticed this as a big problem myself, but that aside, what you're describing is a pathing issue, not a problem with the chain system.
Correct, but the two are very linked. The pathing issue only highlights the problems many have with the chain system. And when characters don't walk through fire to get closer to the selected character (as the chain system compels them to, even when the player didn't want the other characters to move), they might walk in line of sight of another enemy and thus get into an unwanted fight.
Also, for context, BG1&2 also had a relatively bad pathing. But I rarely experienced the problems I experience in BG3. In part because the old system allowed for party formations.
That's the point. Follower pathing is inconsistent, but it really is a completely unrelated issue to the party chain. No matter the mental gymnastics, it's worlds apart in terms of systems under the hood. That's not in terms of disagreeing to be clear, I think both the party management and pathing need a bit of love (or a lot, arguably), but it's important to understand those are two different topics and differentiate between them.
The UI is just a visual representation for a player to interact with a system. That has nothing at all, in the slightest bit, to do with pathing. In any slightest minute way. That doesn't mean the party chain is good. It's just not relevant. It's like saying combat feels slow because there are not enough body options in character creation. That seems like a hyperbole, but it truly is that unrelated (purely and solely technically speaking in game code). I don't know how to underline that any clearer😅 Changing the UI wouldn't impact how companions follow one another in the programming in the slightest, nor whether or not Astarion decides to walk through fire because he needs to stick to formation - But a different control scheme can make it easier/faster for the player to stop Astarion before he do. There's the difference and the overlap of systems that I think is the point you're trying to make? Because I think JandK would agree with that as well - Just butting in here because it strikes me as a both parties agree but don't know they do, kinda.
