> it's faster and easier to create a note in Apple Notes, retrieve it (as they as are sorted from most recent by default, and also I can pin some notes), search, and navigate in folders (especially on mobile, navigating across folders is so much better with Apple Notes than Obsidian).
Yes there are UI elements at play here. But even UI elements are dependent on the language and framework you have decided to use. For example, it is common on Android to use an expanding sidebar whereas on iOS it is more common to use a dropdown menu. If you are developing a one size fits all app then design choices that feel native on one platform are going to feel non-native on another.
And in addition, physical app speed matters. If you want to create a brand new note and you're not already in the app it takes significantly more time until you can start typing with Obsidian than if you use Apple Notes, 1Writer etc. If you're doing it multiple times a day this time adds up.
If you don't think physical app speed matters then why do you think big companies spend thousands optimising webpages to reduce latency? It is because the consumer gets bored of waiting and goes elsewhere. If another app comes along that offers the same functionality of Obsidian but is noticeably faster, people will migrate to it. Everything is a tradeoff, but pretending framework performance isn't a relevant factor does not help anybody.