Debian was quick with adopting it (they've always been very cross-platform focused), in contrast to say Windows (which took a lot longer). On Linux, a lot worked, but not everything. Slowly but surely more got ported to AMD64. What didn't work? Especially pre-compiled proprietary software was not available (IIRC Nvidia drivers? At the very least games). You had to have x86-32 userland installed. Which adds up to higher diskspace requirement. Nowadays, diskspace requirement is negligible, and x86-32 userland is less relevant (on AMD64/x86-64). I would assume the 4 GB limit eventually made games swap to AMD64 as well.

Back then, Intel was still betting on Itanium. It was a time when AMD was ahead of Intel. Wintel lasted longer, and its only since the smartphone revolution they got caught up. In hindsight, even a Windows computer on Intel gave a user more freedom than the locked down stuff on say iOS. OTOH, sometimes user freedom is a bad thing, arguably if the user isn't technically inclined or if you can sell a locked down platform like PlayStation or Xbox for relatively cheap (kind of like the printer business).

I'm sure other people can add to this as well. :-)

Thanks