Signature aggregation would be only on a transaction level, not on a block level as you require interaction between all signing parties, and any party can block

Signature aggregation would be only on a transaction level, not on a block level as you require interaction between all signing parties, and any party can block the signature. You would also have to have some system of making a block, then everybody re-signing their transactions to make the block aggregated- it's just not happening. In Bitcoin today we can do things like make a conditional signature in a multi signature. With three parties, one can pre-sign a transaction and lock it until a future date, then hand it to the other parties who can sign it at their leisure when that time is elapsed. This would not be possible with schnorr unless you also had the expectation that all parties would be online when the lock time expires.