Well that is not the case here, since the amounts are hidden, I would prefer to say:
encrypt(invisible(secret)) 
The problem with Bitcoins transaction graph is that for many transactions the IP and as such the location is known and publicly available, which is a major leak. Being associated to transactions of which the amount is know and the IP is known is not very private.
In the case of Grin, even if my transactions are linked, the only way to have any idea of the amount would be from an endpoint like an exchange, e.g. If a rich user would have a transaction linked to my wallet, only the exchange would know that it is from a rich user. Furthermore they would have a hard time knowing if I paid or received a transaction from that user. Now it could be he bought me or I bought him a cup of coffee or that he donated a million worth in Grin. In either case, his and my identity are not public knowledge and are only available through exchanges to our direct wallet, anything from there is unknown. In case of mined Grin, as long as I do not directly sell to an exchange my identity is unknown. In summary, the information leaked is not that interesting.
To give another example: Buying groceries at a shop
Lets say my identity and a shops identity are known to an exchange.
For Bitcoin, probably my IP and wallet would be known and through the amount I spend, in theory it would be possible to guess what I bought by brute-forcing the combinations of prices of products in the supermarket should equal my spending (Sudoku algorithm also used to break non-equal coinjoins).
In the case of Grin, the amount is not known and an exchange would only be able to known you identity.
The same goes here. Using Grin, only a exchange might know your and the shops identity. Then if you buy something it not easy to deduce whether you bought at the shop or the shop bought something from you. Since the amount is unknown, it would be impossible to know you bought the record from Tchaikovsky and not another record.
So what can be deduced from transaction in Grin?
At best, assuming you bought your Grin at an exchange, your association to other parties that are known at an exchange are known.
Also the timing of your transactions is an information leak. For example, if you buy at a shop, each time at the beginning of the month. It might be deduced you are buying a monthly magazine. If you would receive each time at the end of the month a transaction, it could be speculated you receive your wage/payment in Grin.
In all of the above cases, it is a whole lot of work to make some guesses that cannot be substantiated without doing physical forensics, e.g. asking the shop owner for camera footage. Hiding the transaction amount and hiding directional (could be improved, e.g. by sharing transaction fees) is therefore a major privacy gain.
Should we then be content with the privacy we have? No, I fully agree that we should continue improving, privacy is a goal never fully obtained. With the above examples I just want to illustrated the major benefits of not having addresses, not having an IP leaked and most importantly, having transaction amounts blinded. So yes, hiding transaction amounts is a major privacy gain since that would typically be something that smart algorithms could use to get information about you.
