Not true. Maille armour is both reasonably light and flexible: nowhere near 30 kilos for a hauberk.
Here are some examples from the Wallace Collection- surviving historical pieces
A1 (Late C14th, short sleeved, 74cm long) - 4.5 Kg
A2 (2nd Q C15th, short sleeved, 71cm long) - 8.8 Kg
A3 (1st H...