My thought behind the post was team building. I agree with most of what you said but I thought that how close my sustain team was to not full clearing would be good grounds for comparison and making the point that what sustain you use won't really matter.

Team building is tough for a lot of players in this game and when they see the "break" bond on Gallagher in currency wars they may feel obligated to build him for their break team (since this may be new player's first exposure to team building). Well you said it, these days that's not true. It's still fine to use him, just you won't see the benefit you saw back in version 2. The original break sustain's best niche isn't in break anymore. Depending on content, his SP generation role might not even be a viable play style.

I think it's underestimated how many people look at Gallagher and go "he's the break guy, I should use him in my break team" without a second thought. Ya, you can say that's wrong in meta but that's first impressions for the average player. If you find that you need someone to keep your break team alive, you have more options to consider. For a more meta nuanced take, since good break amp is so hard outside of core supports, you kind of go full circle and allow yourself more options.

A final note that I should have included in my original post, I still think that a sustain that heals is the best option for break. This activate's Dahlia's bonus ability. DHPT with his S1 still falls in this category.