The main disadvantage of the Bitcoin network is the inability to cancel the transaction. Such innovative tool as multisig allows eliminating all problems arising during the transactions confirmation.
This is not a 'disadvantage'. It is a feature.
Multisig does not help to 'eliminate' any 'problems' at all 'during the transactions confirmation'.
As you can see, multi-signature is a very convenient tool for protecting transactions by attracting a third party, which acts as a guarantor of the return of funds to your wallet, in case you are not satisfied with the goods or service.
What you are describing is an escrow service utilizing multi signature.
The problem is that you still have to trust the escrow. And if you do trust the escrow, you don't necessarly need multisignature.
The same could easily be accomplished by sending the full amount to an address fully in control by the escrow.
Then, after consensus between buyer and seller has been reached, the escrow could simply forward the amount paid.
While this pose another risk (escrow stealing funds; which is not possible with multisig escrow), you still need to rely on the escrow to release the funds in case of a dispute when using multisignature.
Multisignature does increase the safety in a trade with an escrow. But it is not a 'tool'.
Using an escrow with multisignature is just one utilization of multisig. There are a lot more. [1]
Please send a merit if you find this article useful.
You might receive merits if your posts would be contentual accurate.
This is not the case. You seem to misunderstand the concept of multisignature (and maybe even bitcoin itself).
[1] Additional applications for multisig:
https://en.bitcoin.it/wiki/Multisignature#Multisignature_Applications