I know my history very well. If you did, you would know that was around the console wars with Microsoft was popping off (360). GTA: SA didn't drop for XBOX originally. SR Series and GTA Series were in the middle of that console war at one point. So if you copped 360, then GTA 3 was your last game in the genre if you moved on with Microsoft. Everybody ain't rich bruh.
Like I stated, SR is objectively better than GTA at the time it dropped. It took the gang concept and made it better, the customization was better, the controls were definately better, and the story was better (minus GTA: SA). It also had vastly superior graphics at the time. There was definately a Volition versus Rockstar debate during that period.