The issue is that most people don't use iPads with keyboards. The windowing system in this case is then an absolute nightmare compared to what came before, as touch-based users were clearly a distant second thought when designing it.
For any HNers who don't have access to iPads running iPadOS 26 / 18, and aren't sure if this is just the "people on the internet hating new things" reflex (it really isn't), here's a side-by-side comparison that clearly illustrates andix's point[1]
[1] https://www.reddit.com/r/iPadOS/comments/1mq8sgd/old_split_v...