...and why IFVs like the CV90/35 are nowhere the same as a BMP-1; it's made to accommodate taller soldiers, today's EU workplace safety regulations are radically different from 1960s Soviet Union standards, and you want thicker armor. So the internal volume is substantially larger, the armor is thicker, the gun heavier, and we're already in the mass range that used to be reserved for 1960s MBTs.
Well, that gun approaches 1960s 90mm AP shot performance as well, in all fairness. Crazy, if you think about it.