No block has 0 prestige with changes.
If you spam the same block 1,000,000 times it will be giving you less and less prestige each time, but never get to 0 (may get so low that you have to add the block 100 times to get an extra 1 prestige since each one is now only giving you 0.01 prestige or something, but never 0). And of course, if you then worked to balance the block variation the prestige would start increasing faster again as all those blocks that previously gave less prestige due to the spam-parade start giving out more again.