The serial number makes it easier to know who donated to whom, but even without it, the govt knows who gave money to the ruling party and who to others. This is how: https://twitter.com/bsindia/status/1199505871723581440

The SBI and, therefore, the govt & the ruling party, know who bought the dodgy Electoral Bonds. The ruling party also knows who among them donated the dodgy bonds to it. Therefore, it can figure out who bought the dodgy bonds but didn’t give it to them.

The ruling party, therefore, knows who bought the dodgy Bonds to give it to others. Every crony donor always understood that the ruling party knew. That is why almost all dodgy Electoral Bonds go to the ruling party. The scheme is designed to make funds flow to the ruling party

Now the numbers do make things easier. Without the numbers, the govt and the ruling party can’t figure out which other party got the funds exactly, though it can make a guess. The numbers take the guesswork out of this.

To sum up, the dodgy Electoral Bonds scheme was designed specifically to make funds flow to the ruling party, and stop it from going to others. That was its only reason for existence, right from the beginning. That IS the core of the scheme.