The earliest memory I have for PS2 limitations excuse was for inventory spaces. People wanted more and more and SE kept saying we can't, PS2 limits us. Then they kept giving us gobbie bags to increase our inventory, wtf? ... After all the PS2 limitation crap they tossed at us from NA release, they said 80 was the actual limit back in Nov2008
(link) and thus came the satchel and (now) sack...
Of course, just because it's MY earliest memory from since I started playing back in Nov2003 doesn't make it the earliest instance of PS2 limitations.