HLS: Is Multivariant Playlist loading sequentially by design?

Hello, I have question about loading multivarant HLS playlist. We currently provide 5 different streams (1 audio, 4 video at different bit rates) served from different hosts, and when observing the loading in a profiler we can see the behavior of
- `ParsingLoadable` loads the master playlist (determined by inspecting the url)
- followed by loading audio track (since it's listed as the first sub playlist) (again, looking at the url, same for below)
- in parallel, loading the first video track (say 128kbps)
- after playlist of first video track is loaded, the second video track is loaded
- and the 3rd playlist after 2nd is loaded etc

Loading of 2nd, 3rd, 4th playlists are done by different `ParsingLoadable`, but they run after each other sequentially instead of in parallel which is puzzling. Am I initializing the player/track extractor incorrectly?