> Anyone with a moderately sized music collection depended entirely on iTunes to manage their library, and were hence locked in to the iPod/iTunes eco-system. There was no reasonable alternative.

Sorry, not true. I had a large music collection, and did not bother with iPod in the early days (and when I tried much later, didn't like scrolling wheel). It did not work with OGG Vorbis, nor could it have any moderate amount of storage. My DAP had 40 GB: iRiver H340. This was around 2003/2004.

I can't be the only person who downloaded mp3s from Limewire and uploaded to my iPod. I think a lot of my friends did that too. Were the majority of iPod users already locked in by that point through the iTunes ecosystem? If so, what locked them in (the song purchases)?

And then, of course, iTunes got steadily and uniformly worse for years.

There were quite a few programs that synced iTunes playlists to non-Apple phones. This supports your assertion that people were dependent on iTunes for library management, but not that there was lock-in to Apple hardware. I feel that it was the seamless ease of iTunes/iPod/iPhone that won, rather than a hard moat.

> Anyone with a moderately sized music collection depended entirely on iTunes to manage their library

I had a fairly big collection and I didn't. Just used a folder structure and copied stuff over to my flash mp3 player (it was maybe 1GiB, maybe less).