Yes it is 100% the truth but maybe you are interpreting that sentence differently by chance?

The intended meaning is this: "Unlike other alternative coins, ROI coins' proof of stake minting and interest payouts are carved in stone." -- ROI coin is different than most all other coins because your payout is carved in stone to be an exact amount. How much you have in your wallet does not matter.. a user that deposits 5 coins will get the same interest as a user that deposits 5 million coins. A user that has their wallet offline for a year will get the same interest as a user who runs their wallet day and night all year. Every user gets the exact same interest no matter what the wallet weight vs. the network weight is. Every user gets the same interest no matter what the age of their coins is. Interest is paid every single block of the blockchain beginning with the first block.

When you stake other coins interest payouts can be inconsistent and nearly impossible to pre-determine. This is because of many variables such as network competition, latency, wallet weight vs. network weight, age of coins, etc., etc.

At the onset of ROI the coin was intended to create a knowable payout system for the users. This means that if you term deposit X coins for X blocks you know the payout in a popup window before you ever even commit to that term deposit.

If by chance you interpreted that sentence to mean that interest payouts would never be altered at any future date this was not the intended meaning. In the early stage of the coin the higher payouts will serve to grow coin supply, community interest and hopefully trading volume. Obviously these rates cannot be sustained forever and at a future date and based on community feedback, market trends, coin valuation and other details the code will be modified to reduce those rates as needed to control any inflation issues.

I am not always the best at explaining things so if this still doesn't make sense let me know