This post is for Arcade. As far as I know, the light MBTs aren’t as penalized in RB.
I own the French 7.7/8.0 premium lineup. The CLOVIS in particular is a good tank. The AMX-30? Not so.
The tanks AMX-30 and Leopard 1, at least their unstabilized variants, are just worse than the less conventional tanks, such as the howitzer tanks like PZH 2000 and DF105.
They offer no protection advantage, and due to layout, actually more vulnerable to all shells but especially APHE than the Mardar light tanks.
At least the M60, T95E1, T-55 are somewhat resistant to APHE.
The AMX/Leo guns also fire way slower.
And if you get uptiered against heavily armored MBTs like T-55AM (yes I know that’s a medium tanks) you’re in a severe disadvantage, so much so that an SPAA or howitzer would be capable of doing more damage to them, either helping the team by spamming 35mm or blowing them up with the 155mm.