

for each file, the computer has to ask the phone about the file, wait for the phone to process the file request, and respond. Then it can start transferring the file. With a single file, it can copy everything in one go without stopping.
You’re basically being bottlenecked by your phone’s CPU, and by high latency in a single-threaded task.

The point of AA is the archiving.
Anyways, from a listening perspective, 160kbit vorbis is audibly lossless I think, and there are many songs on here that are not possible to find elsewhere. For popular songs you want, yeah, just download the Flac elsewhere.