Probably the Sonic Stage software that people were bullied into using. Even today I know of someone who claims they cannot just drag & drop because of sony software stopping them. I tell them they're wrong, they can drag & drop from one window to another... but they won't have it.
The thing wrong with sony was their mechanical moving parts. Cheap plastic buttons, dust getting into CD walkman lazer tracks, minidisc cartridge mechanisms, spring loaded memory card hatches... they all broke on me. The less moving parts for sony the better.