You may want to avoid that blanket statements around developers who've worked with indexeddb, safari's implementation is famously awful, so much so that caniuse makes special note of it.
Assuming we’re still talking about mobile Safari on iOS here, unfortunately that isn’t true in all areas. For example, the way iOS Safari handles HTML5 media elements is essentially to play them through a plug-in. We had to implement a whole new authentication mechanism for a site I work on that serves video content to logged in users, because it wasn’t actually Safari requesting the video resource so we weren’t seeing the user’s ID cookie. There are numerous other problems with how iOS Safari handles video content that make it difficult or impossible to implement other functionality or UI behaviour that would make our site better for our users.