We know the advantages of decentralized however what are the disadvantages of the Decentralized system that we should take note of while using this technology?
Here are the disadvantages which are based on my studying of cryptosystems:
- High hardware requirements
It seems, the world is moving towards cloud-based systems. For example, let's take a look at what Apple is currently selling: MacMini and Macbook Pro are still have the base configuration with only 128 gb SSD, iMacs are still being offered with hard drives (pretty ancient technology at this point). For basic usage that's okay. But if you need to be involved in crypto, you should have a much more capable machine.
Even if you don't intend to mine coins, just to be able to make transactions you are supposed to run a full node. Yeah, there are some workarounds, such as using third-party master nodes or whatever they call them, however, almost all of the available approches are not recommended by security experts. When you don't have your own full node you are relying on someone else's fairness. And, as you may know, humans are not the creatures we can blindly trust.
- Low protection against criminals
In a fully centralised system we know who is responsible for all the good and evil things. If somethings goes wrong (e.g., your money was stolen), you will still have a chance to resolve the issue successfully, because you are protected by the law, and you know the entity you should press charges against.
In a decentralised system you are on your own. If somethings goes wrong and your money's gone, nobody will help you. It's sad, but (at least in current implementations) the only thing you can do in this case is...to move on.
In a centralised system the most important security decisions (e.g., 2FA, MFA, Oauth etc.) were already made for you. In a decentralised world you should invest the time to ensure that your savings are protected taking into account all recent advancement in cryptocurrency infrastructure.
- Possibility of 51% attack
Basically, there is no way to prevent someone from controlling more than 50% of the network's mining hashrate, or computing power. And if this happens, all your coins value will be dropped down to zero because you are no longer protected by the blockchain.
- Hard to implement refund policies
It's hard to image a shop that successfully operates without providing clear refund policies. If you are not 100% satisfied with your purchase, you should have a right to return the product and get a full refund. With constantly increasing complexity of cryptocurrency systems it's getting more and more difficult to incorporate refund features into the shopping flow.
That's what I can tell you regarding disadvantages right off the bat. Personally, I believe that all or almost all of the aforementioned points will be resolved in the future by some talented people who always come up with unpredictable and bright ideas.