I agree BR tends to be a bit better quality, especially as it comes to collabs. I've bought a few pieces through the years (Trina Turk, Marimekko, Milly). I tend to gravitate towards their clothes because their cuts/sizing just fit me off the rack without needing tailoring, so that's disappointing to see about the Peter Do collab's sizing.
When I was younger, I loved having the opportunity to explore different designers' aesthetics without having to save a year to do so. I didn't have to learn with designer prices what does or does not work for me.
Don't get me wrong, I do see collaborations as marketing the brand and similar to limited or special editions when fashion is seasonal and all somewhat limited. Nowadays, it's ultimately about the appeal of the item for me. What makes anything special is choosing items I love, whether one unit was produced or 100,000, and combining it together, not being told it is, but it's been an ever evolving process for me.